Add opt-in anonymous stats reporting (#2249)

* Initial phone home stats queries

* Add userAgent to UpdateDeviceLastSeen
Add new Table for tracking daily user vists

* Add user_daily_visits table

* Fix queries

* userapi stats tables & queries

* userapi interface and internal api

* sycnapi stats queries

* testing phone home stats

* Add complete config to syncapi

* add missing files

* Fix queries

* Send empty request

* Add version & monolith stats

* Add configuration for phone home stats

* Move WASM to its own file, add config and comments

* Add tracing methods

* Add total rooms

* Add more fields, actually send data somewhere

* Move stats to the userapi

* Move phone home stats to util package

* Cleanup

* Linter & parts of GH comments

* More GH comments changes
- Move comments to SQL statements
- Shrink interface, add struct for stats
- No fatal errors, use defaults

* Be more explicit when querying

* Fix wrong calculation & wrong query params
Add tests

* Add Windows stats

* ADd build constraint

* Use new testing structure
Fix issues with getting values when using SQLite
Fix wrong AddDate value
Export UpdateUserDailyVisits

* Fix query params

* Fix test

* Add comment about countR30UsersSQL and countR30UsersV2SQL; fix test

* Update config

* Also update example config file

* Use OS level proxy, update logging

Co-authored-by: kegsay <kegan@matrix.org>

19 files changed, 1543 insertions, 13 deletions

diff --git a/userapi/api/api.go b/userapi/api/api.go
index 6aa6a684..6ab68fa0 100644
--- a/userapi/api/api.go
+++ b/userapi/api/api.go
@@ -320,6 +320,7 @@ type PerformLastSeenUpdateRequest struct {
 	UserID     string
 	DeviceID   string
 	RemoteAddr string
+	UserAgent  string
 }
 
 // PerformLastSeenUpdateResponse is the response for PerformLastSeenUpdate.
diff --git a/userapi/internal/api.go b/userapi/internal/api.go
index be58e2d8..394bfa22 100644
--- a/userapi/internal/api.go
+++ b/userapi/internal/api.go
@@ -210,7 +210,7 @@ func (a *UserInternalAPI) PerformLastSeenUpdate(
 	if err != nil {
 		return fmt.Errorf("gomatrixserverlib.SplitID: %w", err)
 	}
-	if err := a.DB.UpdateDeviceLastSeen(ctx, localpart, req.DeviceID, req.RemoteAddr); err != nil {
+	if err := a.DB.UpdateDeviceLastSeen(ctx, localpart, req.DeviceID, req.RemoteAddr, req.UserAgent); err != nil {
 		return fmt.Errorf("a.DeviceDB.UpdateDeviceLastSeen: %w", err)
 	}
 	return nil
diff --git a/userapi/storage/interface.go b/userapi/storage/interface.go
index a4562cf1..f7cd1810 100644
--- a/userapi/storage/interface.go
+++ b/userapi/storage/interface.go
@@ -22,6 +22,7 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/dendrite/userapi/storage/tables"
+	"github.com/matrix-org/dendrite/userapi/types"
 )
 
 type Profile interface {
@@ -67,7 +68,7 @@ type Device interface {
 	// Returns the device on success.
 	CreateDevice(ctx context.Context, localpart string, deviceID *string, accessToken string, displayName *string, ipAddr, userAgent string) (dev *api.Device, returnErr error)
 	UpdateDevice(ctx context.Context, localpart, deviceID string, displayName *string) error
-	UpdateDeviceLastSeen(ctx context.Context, localpart, deviceID, ipAddr string) error
+	UpdateDeviceLastSeen(ctx context.Context, localpart, deviceID, ipAddr, userAgent string) error
 	RemoveDevices(ctx context.Context, localpart string, devices []string) error
 	// RemoveAllDevices deleted all devices for this user. Returns the devices deleted.
 	RemoveAllDevices(ctx context.Context, localpart, exceptDeviceID string) (devices []api.Device, err error)
@@ -135,9 +136,14 @@ type Database interface {
 	OpenID
 	Profile
 	Pusher
+	Statistics
 	ThreePID
 }
 
+type Statistics interface {
+	UserStatistics(ctx context.Context) (*types.UserStatistics, *types.DatabaseEngine, error)
+}
+
 // Err3PIDInUse is the error returned when trying to save an association involving
 // a third-party identifier which is already associated to a local user.
 var Err3PIDInUse = errors.New("this third-party identifier is already in use")
diff --git a/userapi/storage/postgres/devices_table.go b/userapi/storage/postgres/devices_table.go
index 6c777982..ccb77667 100644
--- a/userapi/storage/postgres/devices_table.go
+++ b/userapi/storage/postgres/devices_table.go
@@ -96,7 +96,7 @@ const selectDevicesByIDSQL = "" +
 	"SELECT device_id, localpart, display_name, last_seen_ts FROM device_devices WHERE device_id = ANY($1) ORDER BY last_seen_ts DESC"
 
 const updateDeviceLastSeen = "" +
-	"UPDATE device_devices SET last_seen_ts = $1, ip = $2 WHERE localpart = $3 AND device_id = $4"
+	"UPDATE device_devices SET last_seen_ts = $1, ip = $2, user_agent = $3 WHERE localpart = $4 AND device_id = $5"
 
 type devicesStatements struct {
 	insertDeviceStmt             *sql.Stmt
@@ -304,9 +304,9 @@ func (s *devicesStatements) SelectDevicesByLocalpart(
 	return devices, rows.Err()
 }
 
-func (s *devicesStatements) UpdateDeviceLastSeen(ctx context.Context, txn *sql.Tx, localpart, deviceID, ipAddr string) error {
+func (s *devicesStatements) UpdateDeviceLastSeen(ctx context.Context, txn *sql.Tx, localpart, deviceID, ipAddr, userAgent string) error {
 	lastSeenTs := time.Now().UnixNano() / 1000000
 	stmt := sqlutil.TxStmt(txn, s.updateDeviceLastSeenStmt)
-	_, err := stmt.ExecContext(ctx, lastSeenTs, ipAddr, localpart, deviceID)
+	_, err := stmt.ExecContext(ctx, lastSeenTs, ipAddr, userAgent, localpart, deviceID)
 	return err
 }
diff --git a/userapi/storage/postgres/stats_table.go b/userapi/storage/postgres/stats_table.go
new file mode 100644
index 00000000..f7190001
--- /dev/null
+++ b/userapi/storage/postgres/stats_table.go
@@ -0,0 +1,437 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	"github.com/lib/pq"
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/dendrite/userapi/storage/tables"
+	"github.com/matrix-org/dendrite/userapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/sirupsen/logrus"
+)
+
+const userDailyVisitsSchema = `
+CREATE TABLE IF NOT EXISTS user_daily_visits (
+    localpart TEXT NOT NULL,
+	device_id TEXT NOT NULL,
+	timestamp BIGINT NOT NULL,
+	user_agent TEXT
+);
+
+-- Device IDs and timestamp must be unique for a given user per day
+CREATE UNIQUE INDEX IF NOT EXISTS localpart_device_timestamp_idx ON user_daily_visits(localpart, device_id, timestamp);
+CREATE INDEX IF NOT EXISTS timestamp_idx ON user_daily_visits(timestamp);
+CREATE INDEX IF NOT EXISTS localpart_timestamp_idx ON user_daily_visits(localpart, timestamp);
+`
+
+const countUsersLastSeenAfterSQL = "" +
+	"SELECT COUNT(*) FROM (" +
+	" SELECT localpart FROM device_devices WHERE last_seen_ts > $1 " +
+	" GROUP BY localpart" +
+	" ) u"
+
+// Note on the following countR30UsersSQL and countR30UsersV2SQL: The different checks are intentional.
+// This is to ensure the values reported by Dendrite are the same as by Synapse.
+// Queries are taken from: https://github.com/matrix-org/synapse/blob/9ce51a47f6e37abd0a1275281806399d874eb026/synapse/storage/databases/main/stats.py
+
+/*
+R30Users counts the number of 30 day retained users, defined as:
+- Users who have created their accounts more than 30 days ago
+- Where last seen at most 30 days ago
+- Where account creation and last_seen are > 30 days apart
+*/
+const countR30UsersSQL = `
+SELECT platform, COUNT(*) FROM (
+	SELECT users.localpart, platform, users.created_ts, MAX(uip.last_seen_ts)
+	FROM account_accounts users
+	INNER JOIN
+	(SELECT 
+		localpart, last_seen_ts,
+		CASE
+	    	WHEN user_agent LIKE '%%Android%%' THEN 'android'
+    	    WHEN user_agent LIKE '%%iOS%%' THEN 'ios'
+        	WHEN user_agent LIKE '%%Electron%%' THEN 'electron'
+        	WHEN user_agent LIKE '%%Mozilla%%' THEN 'web'
+        	WHEN user_agent LIKE '%%Gecko%%' THEN 'web'
+        	ELSE 'unknown'
+		END
+    	AS platform
+		FROM device_devices
+	) uip
+	ON users.localpart = uip.localpart
+	AND users.account_type <> 4
+	AND users.created_ts < $1
+	AND uip.last_seen_ts > $1
+	AND (uip.last_seen_ts) - users.created_ts > $2
+	GROUP BY users.localpart, platform, users.created_ts
+	) u GROUP BY PLATFORM
+`
+
+/*
+R30UsersV2 counts the number of 30 day retained users, defined as users that:
+- Appear more than once in the past 60 days
+- Have more than 30 days between the most and least recent appearances that occurred in the past 60 days.
+*/
+const countR30UsersV2SQL = `
+SELECT
+	client_type,
+    count(client_type)
+FROM 
+	(
+    	SELECT
+        	localpart,
+            CASE
+            	WHEN
+                LOWER(user_agent) LIKE '%%riot%%' OR
+				LOWER(user_agent) LIKE '%%element%%'
+                THEN CASE
+                	WHEN LOWER(user_agent) LIKE '%%electron%%' THEN 'electron'
+					WHEN LOWER(user_agent) LIKE '%%android%%' THEN 'android'
+					WHEN LOWER(user_agent) LIKE '%%ios%%' THEN 'ios'
+					ELSE 'unknown'
+				END
+				WHEN LOWER(user_agent) LIKE '%%mozilla%%' OR LOWER(user_agent) LIKE '%%gecko%%' THEN 'web'
+				ELSE 'unknown'
+			END as client_type
+		FROM user_daily_visits
+		WHERE timestamp > $1 AND timestamp < $2
+		GROUP BY localpart, client_type
+		HAVING max(timestamp) - min(timestamp) > $3
+	) AS temp
+GROUP BY client_type
+`
+
+const countUserByAccountTypeSQL = `
+SELECT COUNT(*) FROM account_accounts WHERE account_type = ANY($1)
+`
+
+// $1 = All non guest AccountType IDs
+// $2 = Guest AccountType
+const countRegisteredUserByTypeStmt = `
+SELECT user_type, COUNT(*) AS count FROM (
+	SELECT
+    CASE
+    	WHEN account_type = ANY($1) AND appservice_id IS NULL THEN 'native'
+        WHEN account_type = $2 AND appservice_id IS NULL THEN 'guest'
+        WHEN account_type = ANY($1) AND appservice_id IS NOT NULL THEN 'bridged'
+	END AS user_type
+    FROM account_accounts
+    WHERE created_ts > $3
+) AS t GROUP BY user_type
+`
+
+// account_type 1 = users; 3 = admins
+const updateUserDailyVisitsSQL = `
+INSERT INTO user_daily_visits(localpart, device_id, timestamp, user_agent)
+	SELECT u.localpart, u.device_id, $1, MAX(u.user_agent)
+	FROM device_devices AS u
+	LEFT JOIN (
+		SELECT localpart, device_id, timestamp FROM user_daily_visits
+		WHERE timestamp = $1
+	) udv
+	ON u.localpart = udv.localpart AND u.device_id = udv.device_id
+	INNER JOIN device_devices d ON d.localpart = u.localpart
+	INNER JOIN account_accounts a ON a.localpart = u.localpart
+	WHERE $2 <= d.last_seen_ts AND d.last_seen_ts < $3
+	AND a.account_type in (1, 3)
+	GROUP BY u.localpart, u.device_id
+ON CONFLICT (localpart, device_id, timestamp) DO NOTHING
+;
+`
+
+const queryDBEngineVersion = "SHOW server_version;"
+
+type statsStatements struct {
+	serverName                    gomatrixserverlib.ServerName
+	lastUpdate                    time.Time
+	countUsersLastSeenAfterStmt   *sql.Stmt
+	countR30UsersStmt             *sql.Stmt
+	countR30UsersV2Stmt           *sql.Stmt
+	updateUserDailyVisitsStmt     *sql.Stmt
+	countUserByAccountTypeStmt    *sql.Stmt
+	countRegisteredUserByTypeStmt *sql.Stmt
+	dbEngineVersionStmt           *sql.Stmt
+}
+
+func NewPostgresStatsTable(db *sql.DB, serverName gomatrixserverlib.ServerName) (tables.StatsTable, error) {
+	s := &statsStatements{
+		serverName: serverName,
+		lastUpdate: time.Now(),
+	}
+
+	_, err := db.Exec(userDailyVisitsSchema)
+	if err != nil {
+		return nil, err
+	}
+	go s.startTimers()
+	return s, sqlutil.StatementList{
+		{&s.countUsersLastSeenAfterStmt, countUsersLastSeenAfterSQL},
+		{&s.countR30UsersStmt, countR30UsersSQL},
+		{&s.countR30UsersV2Stmt, countR30UsersV2SQL},
+		{&s.updateUserDailyVisitsStmt, updateUserDailyVisitsSQL},
+		{&s.countUserByAccountTypeStmt, countUserByAccountTypeSQL},
+		{&s.countRegisteredUserByTypeStmt, countRegisteredUserByTypeStmt},
+		{&s.dbEngineVersionStmt, queryDBEngineVersion},
+	}.Prepare(db)
+}
+
+func (s *statsStatements) startTimers() {
+	var updateStatsFunc func()
+	updateStatsFunc = func() {
+		logrus.Infof("Executing UpdateUserDailyVisits")
+		if err := s.UpdateUserDailyVisits(context.Background(), nil, time.Now(), s.lastUpdate); err != nil {
+			logrus.WithError(err).Error("failed to update daily user visits")
+		}
+		time.AfterFunc(time.Hour*3, updateStatsFunc)
+	}
+	time.AfterFunc(time.Minute*5, updateStatsFunc)
+}
+
+func (s *statsStatements) allUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	stmt := sqlutil.TxStmt(txn, s.countUserByAccountTypeStmt)
+	err = stmt.QueryRowContext(ctx,
+		pq.Int64Array{
+			int64(api.AccountTypeUser),
+			int64(api.AccountTypeGuest),
+			int64(api.AccountTypeAdmin),
+			int64(api.AccountTypeAppService),
+		},
+	).Scan(&result)
+	return
+}
+
+func (s *statsStatements) nonBridgedUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	stmt := sqlutil.TxStmt(txn, s.countUserByAccountTypeStmt)
+	err = stmt.QueryRowContext(ctx,
+		pq.Int64Array{
+			int64(api.AccountTypeUser),
+			int64(api.AccountTypeGuest),
+			int64(api.AccountTypeAdmin),
+		},
+	).Scan(&result)
+	return
+}
+
+func (s *statsStatements) registeredUserByType(ctx context.Context, txn *sql.Tx) (map[string]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.countRegisteredUserByTypeStmt)
+	registeredAfter := time.Now().AddDate(0, 0, -30)
+
+	rows, err := stmt.QueryContext(ctx,
+		pq.Int64Array{
+			int64(api.AccountTypeUser),
+			int64(api.AccountTypeAdmin),
+			int64(api.AccountTypeAppService),
+		},
+		api.AccountTypeGuest,
+		gomatrixserverlib.AsTimestamp(registeredAfter),
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "RegisteredUserByType: failed to close rows")
+
+	var userType string
+	var count int64
+	var result = make(map[string]int64)
+	for rows.Next() {
+		if err = rows.Scan(&userType, &count); err != nil {
+			return nil, err
+		}
+		result[userType] = count
+	}
+
+	return result, rows.Err()
+}
+
+func (s *statsStatements) dailyUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	stmt := sqlutil.TxStmt(txn, s.countUsersLastSeenAfterStmt)
+	lastSeenAfter := time.Now().AddDate(0, 0, -1)
+	err = stmt.QueryRowContext(ctx,
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+	).Scan(&result)
+	return
+}
+
+func (s *statsStatements) monthlyUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	stmt := sqlutil.TxStmt(txn, s.countUsersLastSeenAfterStmt)
+	lastSeenAfter := time.Now().AddDate(0, 0, -30)
+	err = stmt.QueryRowContext(ctx,
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+	).Scan(&result)
+	return
+}
+
+/*
+R30Users counts the number of 30 day retained users, defined as:
+- Users who have created their accounts more than 30 days ago
+- Where last seen at most 30 days ago
+- Where account creation and last_seen are > 30 days apart
+*/
+func (s *statsStatements) r30Users(ctx context.Context, txn *sql.Tx) (map[string]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.countR30UsersStmt)
+	lastSeenAfter := time.Now().AddDate(0, 0, -30)
+	diff := time.Hour * 24 * 30
+
+	rows, err := stmt.QueryContext(ctx,
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+		diff.Milliseconds(),
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "R30Users: failed to close rows")
+
+	var platform string
+	var count int64
+	var result = make(map[string]int64)
+	for rows.Next() {
+		if err = rows.Scan(&platform, &count); err != nil {
+			return nil, err
+		}
+		if platform == "unknown" {
+			continue
+		}
+		result["all"] += count
+		result[platform] = count
+	}
+
+	return result, rows.Err()
+}
+
+/*
+R30UsersV2 counts the number of 30 day retained users, defined as users that:
+- Appear more than once in the past 60 days
+- Have more than 30 days between the most and least recent appearances that occurred in the past 60 days.
+*/
+func (s *statsStatements) r30UsersV2(ctx context.Context, txn *sql.Tx) (map[string]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.countR30UsersV2Stmt)
+	sixtyDaysAgo := time.Now().AddDate(0, 0, -60)
+	diff := time.Hour * 24 * 30
+	tomorrow := time.Now().Add(time.Hour * 24)
+
+	rows, err := stmt.QueryContext(ctx,
+		gomatrixserverlib.AsTimestamp(sixtyDaysAgo),
+		gomatrixserverlib.AsTimestamp(tomorrow),
+		diff.Milliseconds(),
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "R30UsersV2: failed to close rows")
+
+	var platform string
+	var count int64
+	var result = map[string]int64{
+		"ios":      0,
+		"android":  0,
+		"web":      0,
+		"electron": 0,
+		"all":      0,
+	}
+	for rows.Next() {
+		if err = rows.Scan(&platform, &count); err != nil {
+			return nil, err
+		}
+		if _, ok := result[platform]; !ok {
+			continue
+		}
+		result["all"] += count
+		result[platform] = count
+	}
+
+	return result, rows.Err()
+}
+
+// UserStatistics collects some information about users on this instance.
+// Returns the stats itself as well as the database engine version and type.
+// On error, returns the stats collected up to the error.
+func (s *statsStatements) UserStatistics(ctx context.Context, txn *sql.Tx) (*types.UserStatistics, *types.DatabaseEngine, error) {
+	var (
+		stats = &types.UserStatistics{
+			R30UsersV2: map[string]int64{
+				"ios":      0,
+				"android":  0,
+				"web":      0,
+				"electron": 0,
+				"all":      0,
+			},
+			R30Users:              map[string]int64{},
+			RegisteredUsersByType: map[string]int64{},
+		}
+		dbEngine = &types.DatabaseEngine{Engine: "Postgres", Version: "unknown"}
+		err      error
+	)
+	stats.AllUsers, err = s.allUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.DailyUsers, err = s.dailyUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.MonthlyUsers, err = s.monthlyUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.R30Users, err = s.r30Users(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.R30UsersV2, err = s.r30UsersV2(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.NonBridgedUsers, err = s.nonBridgedUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.RegisteredUsersByType, err = s.registeredUserByType(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+
+	stmt := sqlutil.TxStmt(txn, s.dbEngineVersionStmt)
+	err = stmt.QueryRowContext(ctx).Scan(&dbEngine.Version)
+	return stats, dbEngine, err
+}
+
+func (s *statsStatements) UpdateUserDailyVisits(
+	ctx context.Context, txn *sql.Tx,
+	startTime, lastUpdate time.Time,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.updateUserDailyVisitsStmt)
+	startTime = startTime.Truncate(time.Hour * 24)
+
+	// edge case
+	if startTime.After(s.lastUpdate) {
+		startTime = startTime.AddDate(0, 0, -1)
+	}
+	_, err := stmt.ExecContext(ctx,
+		gomatrixserverlib.AsTimestamp(startTime),
+		gomatrixserverlib.AsTimestamp(lastUpdate),
+		gomatrixserverlib.AsTimestamp(time.Now()),
+	)
+	if err == nil {
+		s.lastUpdate = time.Now()
+	}
+	return err
+}
diff --git a/userapi/storage/postgres/storage.go b/userapi/storage/postgres/storage.go
index 74100a72..b9afb5a5 100644
--- a/userapi/storage/postgres/storage.go
+++ b/userapi/storage/postgres/storage.go
@@ -94,6 +94,10 @@ func NewDatabase(base *base.BaseDendrite, dbProperties *config.DatabaseOptions,
 	if err != nil {
 		return nil, fmt.Errorf("NewPostgresNotificationTable: %w", err)
 	}
+	statsTable, err := NewPostgresStatsTable(db, serverName)
+	if err != nil {
+		return nil, fmt.Errorf("NewPostgresStatsTable: %w", err)
+	}
 	return &shared.Database{
 		AccountDatas:          accountDataTable,
 		Accounts:              accountsTable,
@@ -106,6 +110,7 @@ func NewDatabase(base *base.BaseDendrite, dbProperties *config.DatabaseOptions,
 		ThreePIDs:             threePIDTable,
 		Pushers:               pusherTable,
 		Notifications:         notificationsTable,
+		Stats:                 statsTable,
 		ServerName:            serverName,
 		DB:                    db,
 		Writer:                writer,
diff --git a/userapi/storage/shared/storage.go b/userapi/storage/shared/storage.go
index f7212e03..0cf713da 100644
--- a/userapi/storage/shared/storage.go
+++ b/userapi/storage/shared/storage.go
@@ -26,6 +26,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/matrix-org/dendrite/userapi/types"
 	"github.com/matrix-org/gomatrixserverlib"
 	"golang.org/x/crypto/bcrypt"
 
@@ -51,6 +52,7 @@ type Database struct {
 	LoginTokens           tables.LoginTokenTable
 	Notifications         tables.NotificationTable
 	Pushers               tables.PusherTable
+	Stats                 tables.StatsTable
 	LoginTokenLifetime    time.Duration
 	ServerName            gomatrixserverlib.ServerName
 	BcryptCost            int
@@ -611,10 +613,10 @@ func (d *Database) RemoveAllDevices(
 	return
 }
 
-// UpdateDeviceLastSeen updates a the last seen timestamp and the ip address
-func (d *Database) UpdateDeviceLastSeen(ctx context.Context, localpart, deviceID, ipAddr string) error {
+// UpdateDeviceLastSeen updates a last seen timestamp and the ip address.
+func (d *Database) UpdateDeviceLastSeen(ctx context.Context, localpart, deviceID, ipAddr, userAgent string) error {
 	return d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		return d.Devices.UpdateDeviceLastSeen(ctx, txn, localpart, deviceID, ipAddr)
+		return d.Devices.UpdateDeviceLastSeen(ctx, txn, localpart, deviceID, ipAddr, userAgent)
 	})
 }
 
@@ -756,3 +758,8 @@ func (d *Database) RemovePushers(
 		return d.Pushers.DeletePushers(ctx, txn, appid, pushkey)
 	})
 }
+
+// UserStatistics populates types.UserStatistics, used in reports.
+func (d *Database) UserStatistics(ctx context.Context) (*types.UserStatistics, *types.DatabaseEngine, error) {
+	return d.Stats.UserStatistics(ctx, nil)
+}
diff --git a/userapi/storage/sqlite3/devices_table.go b/userapi/storage/sqlite3/devices_table.go
index b86ed1cc..93291e6a 100644
--- a/userapi/storage/sqlite3/devices_table.go
+++ b/userapi/storage/sqlite3/devices_table.go
@@ -81,7 +81,7 @@ const selectDevicesByIDSQL = "" +
 	"SELECT device_id, localpart, display_name, last_seen_ts FROM device_devices WHERE device_id IN ($1) ORDER BY last_seen_ts DESC"
 
 const updateDeviceLastSeen = "" +
-	"UPDATE device_devices SET last_seen_ts = $1, ip = $2 WHERE localpart = $3 AND device_id = $4"
+	"UPDATE device_devices SET last_seen_ts = $1, ip = $2, user_agent = $3 WHERE localpart = $4 AND device_id = $5"
 
 type devicesStatements struct {
 	db                           *sql.DB
@@ -306,9 +306,9 @@ func (s *devicesStatements) SelectDevicesByID(ctx context.Context, deviceIDs []s
 	return devices, rows.Err()
 }
 
-func (s *devicesStatements) UpdateDeviceLastSeen(ctx context.Context, txn *sql.Tx, localpart, deviceID, ipAddr string) error {
+func (s *devicesStatements) UpdateDeviceLastSeen(ctx context.Context, txn *sql.Tx, localpart, deviceID, ipAddr, userAgent string) error {
 	lastSeenTs := time.Now().UnixNano() / 1000000
 	stmt := sqlutil.TxStmt(txn, s.updateDeviceLastSeenStmt)
-	_, err := stmt.ExecContext(ctx, lastSeenTs, ipAddr, localpart, deviceID)
+	_, err := stmt.ExecContext(ctx, lastSeenTs, ipAddr, userAgent, localpart, deviceID)
 	return err
 }
diff --git a/userapi/storage/sqlite3/stats_table.go b/userapi/storage/sqlite3/stats_table.go
new file mode 100644
index 00000000..af4c7ff9
--- /dev/null
+++ b/userapi/storage/sqlite3/stats_table.go
@@ -0,0 +1,452 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sqlite3
+
+import (
+	"context"
+	"database/sql"
+	"strings"
+	"time"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/dendrite/userapi/storage/tables"
+	"github.com/matrix-org/dendrite/userapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/sirupsen/logrus"
+)
+
+const userDailyVisitsSchema = `
+CREATE TABLE IF NOT EXISTS user_daily_visits (
+    localpart TEXT NOT NULL,
+	device_id TEXT NOT NULL,
+	timestamp BIGINT NOT NULL,
+	user_agent TEXT
+);
+
+-- Device IDs and timestamp must be unique for a given user per day
+CREATE UNIQUE INDEX IF NOT EXISTS localpart_device_timestamp_idx ON user_daily_visits(localpart, device_id, timestamp);
+CREATE INDEX IF NOT EXISTS timestamp_idx ON user_daily_visits(timestamp);
+CREATE INDEX IF NOT EXISTS localpart_timestamp_idx ON user_daily_visits(localpart, timestamp);
+`
+
+const countUsersLastSeenAfterSQL = "" +
+	"SELECT COUNT(*) FROM (" +
+	" SELECT localpart FROM device_devices WHERE last_seen_ts > $1 " +
+	" GROUP BY localpart" +
+	" ) u"
+
+// Note on the following countR30UsersSQL and countR30UsersV2SQL: The different checks are intentional.
+// This is to ensure the values reported by Dendrite are the same as by Synapse.
+// Queries are taken from: https://github.com/matrix-org/synapse/blob/9ce51a47f6e37abd0a1275281806399d874eb026/synapse/storage/databases/main/stats.py
+
+/*
+R30Users counts the number of 30 day retained users, defined as:
+- Users who have created their accounts more than 30 days ago
+- Where last seen at most 30 days ago
+- Where account creation and last_seen are > 30 days apart
+*/
+const countR30UsersSQL = `
+SELECT platform, COUNT(*) FROM (
+	SELECT users.localpart, platform, users.created_ts, MAX(uip.last_seen_ts)
+	FROM account_accounts users
+	INNER JOIN
+	(SELECT 
+		localpart, last_seen_ts,
+		CASE
+	    	WHEN user_agent LIKE '%%Android%%' THEN 'android'
+    	    WHEN user_agent LIKE '%%iOS%%' THEN 'ios'
+        	WHEN user_agent LIKE '%%Electron%%' THEN 'electron'
+        	WHEN user_agent LIKE '%%Mozilla%%' THEN 'web'
+        	WHEN user_agent LIKE '%%Gecko%%' THEN 'web'
+        	ELSE 'unknown'
+		END
+    	AS platform
+		FROM device_devices
+	) uip
+	ON users.localpart = uip.localpart
+	AND users.account_type <> 4
+	AND users.created_ts < $1
+	AND uip.last_seen_ts > $2
+	AND (uip.last_seen_ts) - users.created_ts > $3
+	GROUP BY users.localpart, platform, users.created_ts
+	) u GROUP BY PLATFORM
+`
+
+// Note on the following countR30UsersSQL and countR30UsersV2SQL: The different checks are intentional.
+// This is to ensure the values reported are the same as Synapse reports.
+// Queries are taken from: https://github.com/matrix-org/synapse/blob/9ce51a47f6e37abd0a1275281806399d874eb026/synapse/storage/databases/main/stats.py
+
+/*
+R30UsersV2 counts the number of 30 day retained users, defined as users that:
+- Appear more than once in the past 60 days
+- Have more than 30 days between the most and least recent appearances that occurred in the past 60 days.
+*/
+const countR30UsersV2SQL = `
+SELECT
+	client_type,
+    count(client_type)
+FROM 
+	(
+    	SELECT
+        	localpart,
+            CASE
+            	WHEN
+                LOWER(user_agent) LIKE '%%riot%%' OR
+				LOWER(user_agent) LIKE '%%element%%'
+                THEN CASE
+                	WHEN LOWER(user_agent) LIKE '%%electron%%' THEN 'electron'
+					WHEN LOWER(user_agent) LIKE '%%android%%' THEN 'android'
+					WHEN LOWER(user_agent) LIKE '%%ios%%' THEN 'ios'
+					ELSE 'unknown'
+				END
+				WHEN LOWER(user_agent) LIKE '%%mozilla%%' OR LOWER(user_agent) LIKE '%%gecko%%' THEN 'web'
+				ELSE 'unknown'
+			END as client_type
+		FROM user_daily_visits
+		WHERE timestamp > $1 AND timestamp < $2
+		GROUP BY localpart, client_type
+		HAVING max(timestamp) - min(timestamp) > $3
+	) AS temp
+GROUP BY client_type
+`
+
+const countUserByAccountTypeSQL = `
+SELECT COUNT(*) FROM account_accounts WHERE account_type IN ($1)
+`
+
+// $1 = Guest AccountType
+// $3 & $4 = All non guest AccountType IDs
+const countRegisteredUserByTypeSQL = `
+SELECT user_type, COUNT(*) AS count FROM (
+	SELECT
+    CASE
+    	WHEN account_type IN ($1) AND appservice_id IS NULL THEN 'native'
+        WHEN account_type = $4 AND appservice_id IS NULL THEN 'guest'
+		WHEN account_type IN ($5) AND appservice_id IS NOT NULL THEN 'bridged'
+	END AS user_type
+    FROM account_accounts
+    WHERE created_ts > $8
+) AS t GROUP BY user_type
+`
+
+// account_type 1 = users; 3 = admins
+const updateUserDailyVisitsSQL = `
+INSERT INTO user_daily_visits(localpart, device_id, timestamp, user_agent)
+	SELECT u.localpart, u.device_id, $1, MAX(u.user_agent)
+	FROM device_devices AS u
+	LEFT JOIN (
+		SELECT localpart, device_id, timestamp FROM user_daily_visits
+		WHERE timestamp = $1
+	) udv
+	ON u.localpart = udv.localpart AND u.device_id = udv.device_id
+	INNER JOIN device_devices d ON d.localpart = u.localpart
+	INNER JOIN account_accounts a ON a.localpart = u.localpart
+	WHERE $2 <= d.last_seen_ts AND d.last_seen_ts < $3
+	AND a.account_type in (1, 3)
+	GROUP BY u.localpart, u.device_id
+ON CONFLICT (localpart, device_id, timestamp) DO NOTHING
+;
+`
+
+const queryDBEngineVersion = "select sqlite_version();"
+
+type statsStatements struct {
+	serverName                    gomatrixserverlib.ServerName
+	db                            *sql.DB
+	lastUpdate                    time.Time
+	countUsersLastSeenAfterStmt   *sql.Stmt
+	countR30UsersStmt             *sql.Stmt
+	countR30UsersV2Stmt           *sql.Stmt
+	updateUserDailyVisitsStmt     *sql.Stmt
+	countUserByAccountTypeStmt    *sql.Stmt
+	countRegisteredUserByTypeStmt *sql.Stmt
+	dbEngineVersionStmt           *sql.Stmt
+}
+
+func NewSQLiteStatsTable(db *sql.DB, serverName gomatrixserverlib.ServerName) (tables.StatsTable, error) {
+	s := &statsStatements{
+		serverName: serverName,
+		lastUpdate: time.Now(),
+		db:         db,
+	}
+
+	_, err := db.Exec(userDailyVisitsSchema)
+	if err != nil {
+		return nil, err
+	}
+	go s.startTimers()
+	return s, sqlutil.StatementList{
+		{&s.countUsersLastSeenAfterStmt, countUsersLastSeenAfterSQL},
+		{&s.countR30UsersStmt, countR30UsersSQL},
+		{&s.countR30UsersV2Stmt, countR30UsersV2SQL},
+		{&s.updateUserDailyVisitsStmt, updateUserDailyVisitsSQL},
+		{&s.countUserByAccountTypeStmt, countUserByAccountTypeSQL},
+		{&s.countRegisteredUserByTypeStmt, countRegisteredUserByTypeSQL},
+		{&s.dbEngineVersionStmt, queryDBEngineVersion},
+	}.Prepare(db)
+}
+
+func (s *statsStatements) startTimers() {
+	var updateStatsFunc func()
+	updateStatsFunc = func() {
+		logrus.Infof("Executing UpdateUserDailyVisits")
+		if err := s.UpdateUserDailyVisits(context.Background(), nil, time.Now(), s.lastUpdate); err != nil {
+			logrus.WithError(err).Error("failed to update daily user visits")
+		}
+		time.AfterFunc(time.Hour*3, updateStatsFunc)
+	}
+	time.AfterFunc(time.Minute*5, updateStatsFunc)
+}
+
+func (s *statsStatements) allUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	query := strings.Replace(countUserByAccountTypeSQL, "($1)", sqlutil.QueryVariadic(4), 1)
+	queryStmt, err := s.db.Prepare(query)
+	if err != nil {
+		return 0, err
+	}
+	stmt := sqlutil.TxStmt(txn, queryStmt)
+	err = stmt.QueryRowContext(ctx,
+		1, 2, 3, 4,
+	).Scan(&result)
+	return
+}
+
+func (s *statsStatements) nonBridgedUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	query := strings.Replace(countUserByAccountTypeSQL, "($1)", sqlutil.QueryVariadic(3), 1)
+	queryStmt, err := s.db.Prepare(query)
+	if err != nil {
+		return 0, err
+	}
+	stmt := sqlutil.TxStmt(txn, queryStmt)
+	err = stmt.QueryRowContext(ctx,
+		1, 2, 3,
+	).Scan(&result)
+	return
+}
+
+func (s *statsStatements) registeredUserByType(ctx context.Context, txn *sql.Tx) (map[string]int64, error) {
+	// $1 = Guest AccountType; $2 = timestamp
+	// $3 & $4 = All non guest AccountType IDs
+	nonGuests := []api.AccountType{api.AccountTypeUser, api.AccountTypeAdmin, api.AccountTypeAppService}
+	countSQL := strings.Replace(countRegisteredUserByTypeSQL, "($1)", sqlutil.QueryVariadicOffset(len(nonGuests), 0), 1)
+	countSQL = strings.Replace(countSQL, "($5)", sqlutil.QueryVariadicOffset(len(nonGuests), 1+len(nonGuests)), 1)
+	queryStmt, err := s.db.Prepare(countSQL)
+	if err != nil {
+		return nil, err
+	}
+	stmt := sqlutil.TxStmt(txn, queryStmt)
+	registeredAfter := time.Now().AddDate(0, 0, -30)
+
+	params := make([]interface{}, len(nonGuests)*2+2)
+	// nonGuests is used twice
+	for i, v := range nonGuests {
+		params[i] = v                  // i: 0 1 2 => ($1, $2, $3)
+		params[i+1+len(nonGuests)] = v // i: 4 5 6 => ($5, $6, $7)
+	}
+	params[3] = api.AccountTypeGuest                           // $4
+	params[7] = gomatrixserverlib.AsTimestamp(registeredAfter) // $8
+
+	rows, err := stmt.QueryContext(ctx, params...)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "RegisteredUserByType: failed to close rows")
+
+	var userType string
+	var count int64
+	var result = make(map[string]int64)
+	for rows.Next() {
+		if err = rows.Scan(&userType, &count); err != nil {
+			return nil, err
+		}
+		result[userType] = count
+	}
+
+	return result, rows.Err()
+}
+
+func (s *statsStatements) dailyUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	stmt := sqlutil.TxStmt(txn, s.countUsersLastSeenAfterStmt)
+	lastSeenAfter := time.Now().AddDate(0, 0, -1)
+	err = stmt.QueryRowContext(ctx,
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+	).Scan(&result)
+	return
+}
+
+func (s *statsStatements) monthlyUsers(ctx context.Context, txn *sql.Tx) (result int64, err error) {
+	stmt := sqlutil.TxStmt(txn, s.countUsersLastSeenAfterStmt)
+	lastSeenAfter := time.Now().AddDate(0, 0, -30)
+	err = stmt.QueryRowContext(ctx,
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+	).Scan(&result)
+	return
+}
+
+/* R30Users counts the number of 30 day retained users, defined as:
+- Users who have created their accounts more than 30 days ago
+- Where last seen at most 30 days ago
+- Where account creation and last_seen are > 30 days apart
+*/
+func (s *statsStatements) r30Users(ctx context.Context, txn *sql.Tx) (map[string]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.countR30UsersStmt)
+	lastSeenAfter := time.Now().AddDate(0, 0, -30)
+	diff := time.Hour * 24 * 30
+
+	rows, err := stmt.QueryContext(ctx,
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+		gomatrixserverlib.AsTimestamp(lastSeenAfter),
+		diff.Milliseconds(),
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "R30Users: failed to close rows")
+
+	var platform string
+	var count int64
+	var result = make(map[string]int64)
+	for rows.Next() {
+		if err = rows.Scan(&platform, &count); err != nil {
+			return nil, err
+		}
+		if platform == "unknown" {
+			continue
+		}
+		result["all"] += count
+		result[platform] = count
+	}
+
+	return result, rows.Err()
+}
+
+/* R30UsersV2 counts the number of 30 day retained users, defined as users that:
+- Appear more than once in the past 60 days
+- Have more than 30 days between the most and least recent appearances that occurred in the past 60 days.
+*/
+func (s *statsStatements) r30UsersV2(ctx context.Context, txn *sql.Tx) (map[string]int64, error) {
+	stmt := sqlutil.TxStmt(txn, s.countR30UsersV2Stmt)
+	sixtyDaysAgo := time.Now().AddDate(0, 0, -60)
+	diff := time.Hour * 24 * 30
+	tomorrow := time.Now().Add(time.Hour * 24)
+
+	rows, err := stmt.QueryContext(ctx,
+		gomatrixserverlib.AsTimestamp(sixtyDaysAgo),
+		gomatrixserverlib.AsTimestamp(tomorrow),
+		diff.Milliseconds(),
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "R30UsersV2: failed to close rows")
+
+	var platform string
+	var count int64
+	var result = map[string]int64{
+		"ios":      0,
+		"android":  0,
+		"web":      0,
+		"electron": 0,
+		"all":      0,
+	}
+	for rows.Next() {
+		if err = rows.Scan(&platform, &count); err != nil {
+			return nil, err
+		}
+		if _, ok := result[platform]; !ok {
+			continue
+		}
+		result["all"] += count
+		result[platform] = count
+	}
+	return result, rows.Err()
+}
+
+// UserStatistics collects some information about users on this instance.
+// Returns the stats itself as well as the database engine version and type.
+// On error, returns the stats collected up to the error.
+func (s *statsStatements) UserStatistics(ctx context.Context, txn *sql.Tx) (*types.UserStatistics, *types.DatabaseEngine, error) {
+	var (
+		stats = &types.UserStatistics{
+			R30UsersV2: map[string]int64{
+				"ios":      0,
+				"android":  0,
+				"web":      0,
+				"electron": 0,
+				"all":      0,
+			},
+			R30Users:              map[string]int64{},
+			RegisteredUsersByType: map[string]int64{},
+		}
+		dbEngine = &types.DatabaseEngine{Engine: "SQLite", Version: "unknown"}
+		err      error
+	)
+	stats.AllUsers, err = s.allUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.DailyUsers, err = s.dailyUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.MonthlyUsers, err = s.monthlyUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.R30Users, err = s.r30Users(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.R30UsersV2, err = s.r30UsersV2(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.NonBridgedUsers, err = s.nonBridgedUsers(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+	stats.RegisteredUsersByType, err = s.registeredUserByType(ctx, txn)
+	if err != nil {
+		return stats, dbEngine, err
+	}
+
+	stmt := sqlutil.TxStmt(txn, s.dbEngineVersionStmt)
+	err = stmt.QueryRowContext(ctx).Scan(&dbEngine.Version)
+	return stats, dbEngine, err
+}
+
+func (s *statsStatements) UpdateUserDailyVisits(
+	ctx context.Context, txn *sql.Tx,
+	startTime, lastUpdate time.Time,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.updateUserDailyVisitsStmt)
+	startTime = startTime.Truncate(time.Hour * 24)
+
+	// edge case
+	if startTime.After(s.lastUpdate) {
+		startTime = startTime.AddDate(0, 0, -1)
+	}
+	_, err := stmt.ExecContext(ctx,
+		gomatrixserverlib.AsTimestamp(startTime),
+		gomatrixserverlib.AsTimestamp(lastUpdate),
+		gomatrixserverlib.AsTimestamp(time.Now()),
+	)
+	if err == nil {
+		s.lastUpdate = time.Now()
+	}
+	return err
+}
diff --git a/userapi/storage/sqlite3/storage.go b/userapi/storage/sqlite3/storage.go
index 6858d3d1..a822f687 100644
--- a/userapi/storage/sqlite3/storage.go
+++ b/userapi/storage/sqlite3/storage.go
@@ -95,6 +95,10 @@ func NewDatabase(base *base.BaseDendrite, dbProperties *config.DatabaseOptions,
 	if err != nil {
 		return nil, fmt.Errorf("NewPostgresNotificationTable: %w", err)
 	}
+	statsTable, err := NewSQLiteStatsTable(db, serverName)
+	if err != nil {
+		return nil, fmt.Errorf("NewSQLiteStatsTable: %w", err)
+	}
 	return &shared.Database{
 		AccountDatas:          accountDataTable,
 		Accounts:              accountsTable,
@@ -107,6 +111,7 @@ func NewDatabase(base *base.BaseDendrite, dbProperties *config.DatabaseOptions,
 		ThreePIDs:             threePIDTable,
 		Pushers:               pusherTable,
 		Notifications:         notificationsTable,
+		Stats:                 statsTable,
 		ServerName:            serverName,
 		DB:                    db,
 		Writer:                writer,
diff --git a/userapi/storage/storage_test.go b/userapi/storage/storage_test.go
index 79d5a8da..5683fe06 100644
--- a/userapi/storage/storage_test.go
+++ b/userapi/storage/storage_test.go
@@ -174,7 +174,7 @@ func Test_Devices(t *testing.T) {
 		newName := "new display name"
 		err = db.UpdateDevice(ctx, localpart, deviceWithID.ID, &newName)
 		assert.NoError(t, err, "unable to update device displayname")
-		err = db.UpdateDeviceLastSeen(ctx, localpart, deviceWithID.ID, "127.0.0.1")
+		err = db.UpdateDeviceLastSeen(ctx, localpart, deviceWithID.ID, "127.0.0.1", "Element Web")
 		assert.NoError(t, err, "unable to update device last seen")
 
 		deviceWithID.DisplayName = newName
diff --git a/userapi/storage/tables/interface.go b/userapi/storage/tables/interface.go
index eb0cae31..2fe95567 100644
--- a/userapi/storage/tables/interface.go
+++ b/userapi/storage/tables/interface.go
@@ -18,9 +18,11 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"time"
 
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/dendrite/userapi/types"
 )
 
 type AccountDataTable interface {
@@ -48,7 +50,7 @@ type DevicesTable interface {
 	SelectDeviceByID(ctx context.Context, localpart, deviceID string) (*api.Device, error)
 	SelectDevicesByLocalpart(ctx context.Context, txn *sql.Tx, localpart, exceptDeviceID string) ([]api.Device, error)
 	SelectDevicesByID(ctx context.Context, deviceIDs []string) ([]api.Device, error)
-	UpdateDeviceLastSeen(ctx context.Context, txn *sql.Tx, localpart, deviceID, ipAddr string) error
+	UpdateDeviceLastSeen(ctx context.Context, txn *sql.Tx, localpart, deviceID, ipAddr, userAgent string) error
 }
 
 type KeyBackupTable interface {
@@ -111,6 +113,11 @@ type NotificationTable interface {
 	SelectRoomCounts(ctx context.Context, txn *sql.Tx, localpart, roomID string) (total int64, highlight int64, _ error)
 }
 
+type StatsTable interface {
+	UserStatistics(ctx context.Context, txn *sql.Tx) (*types.UserStatistics, *types.DatabaseEngine, error)
+	UpdateUserDailyVisits(ctx context.Context, txn *sql.Tx, startTime, lastUpdate time.Time) error
+}
+
 type NotificationFilter uint32
 
 const (
diff --git a/userapi/storage/tables/stats_table_test.go b/userapi/storage/tables/stats_table_test.go
new file mode 100644
index 00000000..11521c8b
--- /dev/null
+++ b/userapi/storage/tables/stats_table_test.go
@@ -0,0 +1,319 @@
+package tables_test
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/test"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/dendrite/userapi/storage/postgres"
+	"github.com/matrix-org/dendrite/userapi/storage/sqlite3"
+	"github.com/matrix-org/dendrite/userapi/storage/tables"
+	"github.com/matrix-org/dendrite/userapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+func mustMakeDBs(t *testing.T, dbType test.DBType) (
+	*sql.DB, tables.AccountsTable, tables.DevicesTable, tables.StatsTable, func(),
+) {
+	t.Helper()
+
+	var (
+		accTable   tables.AccountsTable
+		devTable   tables.DevicesTable
+		statsTable tables.StatsTable
+		err        error
+	)
+
+	connStr, close := test.PrepareDBConnectionString(t, dbType)
+	db, err := sqlutil.Open(&config.DatabaseOptions{
+		ConnectionString: config.DataSource(connStr),
+	}, nil)
+	if err != nil {
+		t.Fatalf("failed to open db: %s", err)
+	}
+
+	switch dbType {
+	case test.DBTypeSQLite:
+		accTable, err = sqlite3.NewSQLiteAccountsTable(db, "localhost")
+		if err != nil {
+			t.Fatalf("unable to create acc db: %v", err)
+		}
+		devTable, err = sqlite3.NewSQLiteDevicesTable(db, "localhost")
+		if err != nil {
+			t.Fatalf("unable to open device db: %v", err)
+		}
+		statsTable, err = sqlite3.NewSQLiteStatsTable(db, "localhost")
+		if err != nil {
+			t.Fatalf("unable to open stats db: %v", err)
+		}
+	case test.DBTypePostgres:
+		accTable, err = postgres.NewPostgresAccountsTable(db, "localhost")
+		if err != nil {
+			t.Fatalf("unable to create acc db: %v", err)
+		}
+		devTable, err = postgres.NewPostgresDevicesTable(db, "localhost")
+		if err != nil {
+			t.Fatalf("unable to open device db: %v", err)
+		}
+		statsTable, err = postgres.NewPostgresStatsTable(db, "localhost")
+		if err != nil {
+			t.Fatalf("unable to open stats db: %v", err)
+		}
+	}
+
+	return db, accTable, devTable, statsTable, close
+}
+
+func mustMakeAccountAndDevice(
+	t *testing.T,
+	ctx context.Context,
+	accDB tables.AccountsTable,
+	devDB tables.DevicesTable,
+	localpart string,
+	accType api.AccountType,
+	userAgent string,
+) {
+	t.Helper()
+
+	appServiceID := ""
+	if accType == api.AccountTypeAppService {
+		appServiceID = util.RandomString(16)
+	}
+
+	_, err := accDB.InsertAccount(ctx, nil, localpart, "", appServiceID, accType)
+	if err != nil {
+		t.Fatalf("unable to create account: %v", err)
+	}
+	_, err = devDB.InsertDevice(ctx, nil, "deviceID", localpart, util.RandomString(16), nil, "", userAgent)
+	if err != nil {
+		t.Fatalf("unable to create device: %v", err)
+	}
+}
+
+func mustUpdateDeviceLastSeen(
+	t *testing.T,
+	ctx context.Context,
+	db *sql.DB,
+	localpart string,
+	timestamp time.Time,
+) {
+	t.Helper()
+	_, err := db.ExecContext(ctx, "UPDATE device_devices SET last_seen_ts = $1 WHERE localpart = $2", gomatrixserverlib.AsTimestamp(timestamp), localpart)
+	if err != nil {
+		t.Fatalf("unable to update device last seen")
+	}
+}
+
+func mustUserUpdateRegistered(
+	t *testing.T,
+	ctx context.Context,
+	db *sql.DB,
+	localpart string,
+	timestamp time.Time,
+) {
+	_, err := db.ExecContext(ctx, "UPDATE account_accounts SET created_ts = $1 WHERE localpart = $2", gomatrixserverlib.AsTimestamp(timestamp), localpart)
+	if err != nil {
+		t.Fatalf("unable to update device last seen")
+	}
+}
+
+// These tests must run sequentially, as they build up on each other
+func Test_UserStatistics(t *testing.T) {
+
+	ctx := context.Background()
+	test.WithAllDatabases(t, func(t *testing.T, dbType test.DBType) {
+		db, accDB, devDB, statsDB, close := mustMakeDBs(t, dbType)
+		defer close()
+		wantType := "SQLite"
+		if dbType == test.DBTypePostgres {
+			wantType = "Postgres"
+		}
+
+		t.Run(fmt.Sprintf("want %s database engine", wantType), func(t *testing.T) {
+			_, gotDB, err := statsDB.UserStatistics(ctx, nil)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			if wantType != gotDB.Engine { // can't use DeepEqual, as the Version might differ
+				t.Errorf("UserStatistics() got DB engine = %+v, want %s", gotDB.Engine, wantType)
+			}
+		})
+
+		t.Run("Want Users", func(t *testing.T) {
+			mustMakeAccountAndDevice(t, ctx, accDB, devDB, "user1", api.AccountTypeUser, "Element Android")
+			mustMakeAccountAndDevice(t, ctx, accDB, devDB, "user2", api.AccountTypeUser, "Element iOS")
+			mustMakeAccountAndDevice(t, ctx, accDB, devDB, "user3", api.AccountTypeUser, "Element web")
+			mustMakeAccountAndDevice(t, ctx, accDB, devDB, "user4", api.AccountTypeGuest, "Element Electron")
+			mustMakeAccountAndDevice(t, ctx, accDB, devDB, "user5", api.AccountTypeAdmin, "gecko")
+			mustMakeAccountAndDevice(t, ctx, accDB, devDB, "user6", api.AccountTypeAppService, "gecko")
+			gotStats, _, err := statsDB.UserStatistics(ctx, nil)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			wantStats := &types.UserStatistics{
+				RegisteredUsersByType: map[string]int64{
+					"native":  4,
+					"guest":   1,
+					"bridged": 1,
+				},
+				R30Users: map[string]int64{},
+				R30UsersV2: map[string]int64{
+					"ios":      0,
+					"android":  0,
+					"web":      0,
+					"electron": 0,
+					"all":      0,
+				},
+				AllUsers:        6,
+				NonBridgedUsers: 5,
+				DailyUsers:      6,
+				MonthlyUsers:    6,
+			}
+			if !reflect.DeepEqual(gotStats, wantStats) {
+				t.Errorf("UserStatistics() gotStats = \n%+v\nwant\n%+v", gotStats, wantStats)
+			}
+		})
+
+		t.Run("Users not active for one/two month", func(t *testing.T) {
+			mustUpdateDeviceLastSeen(t, ctx, db, "user1", time.Now().AddDate(0, -2, 0))
+			mustUpdateDeviceLastSeen(t, ctx, db, "user2", time.Now().AddDate(0, -1, 0))
+			gotStats, _, err := statsDB.UserStatistics(ctx, nil)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			wantStats := &types.UserStatistics{
+				RegisteredUsersByType: map[string]int64{
+					"native":  4,
+					"guest":   1,
+					"bridged": 1,
+				},
+				R30Users: map[string]int64{},
+				R30UsersV2: map[string]int64{
+					"ios":      0,
+					"android":  0,
+					"web":      0,
+					"electron": 0,
+					"all":      0,
+				},
+				AllUsers:        6,
+				NonBridgedUsers: 5,
+				DailyUsers:      4,
+				MonthlyUsers:    4,
+			}
+			if !reflect.DeepEqual(gotStats, wantStats) {
+				t.Errorf("UserStatistics() gotStats = \n%+v\nwant\n%+v", gotStats, wantStats)
+			}
+		})
+
+		/* R30Users counts the number of 30 day retained users, defined as:
+		- Users who have created their accounts more than 30 days ago
+		- Where last seen at most 30 days ago
+		- Where account creation and last_seen are > 30 days apart
+		*/
+		t.Run("R30Users tests", func(t *testing.T) {
+			mustUserUpdateRegistered(t, ctx, db, "user1", time.Now().AddDate(0, -2, 0))
+			mustUpdateDeviceLastSeen(t, ctx, db, "user1", time.Now())
+			mustUserUpdateRegistered(t, ctx, db, "user4", time.Now().AddDate(0, -2, 0))
+			mustUpdateDeviceLastSeen(t, ctx, db, "user4", time.Now())
+			startTime := time.Now().AddDate(0, 0, -2)
+			err := statsDB.UpdateUserDailyVisits(ctx, nil, startTime, startTime.Truncate(time.Hour*24).Add(time.Hour))
+			if err != nil {
+				t.Fatalf("unable to update daily visits stats: %v", err)
+			}
+
+			gotStats, _, err := statsDB.UserStatistics(ctx, nil)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			wantStats := &types.UserStatistics{
+				RegisteredUsersByType: map[string]int64{
+					"native":  3,
+					"bridged": 1,
+				},
+				R30Users: map[string]int64{
+					"all":      2,
+					"android":  1,
+					"electron": 1,
+				},
+				R30UsersV2: map[string]int64{
+					"ios":      0,
+					"android":  0,
+					"web":      0,
+					"electron": 0,
+					"all":      0,
+				},
+				AllUsers:        6,
+				NonBridgedUsers: 5,
+				DailyUsers:      5,
+				MonthlyUsers:    5,
+			}
+			if !reflect.DeepEqual(gotStats, wantStats) {
+				t.Errorf("UserStatistics() gotStats = \n%+v\nwant\n%+v", gotStats, wantStats)
+			}
+		})
+
+		/*
+			R30UsersV2 counts the number of 30 day retained users, defined as users that:
+			- Appear more than once in the past 60 days
+			- Have more than 30 days between the most and least recent appearances that occurred in the past 60 days.
+			most recent -> neueste
+			least recent -> älteste
+
+		*/
+		t.Run("R30UsersV2 tests", func(t *testing.T) {
+			// generate some data
+			for i := 100; i > 0; i-- {
+				mustUpdateDeviceLastSeen(t, ctx, db, "user1", time.Now().AddDate(0, 0, -i))
+				mustUpdateDeviceLastSeen(t, ctx, db, "user5", time.Now().AddDate(0, 0, -i))
+				startTime := time.Now().AddDate(0, 0, -i)
+				err := statsDB.UpdateUserDailyVisits(ctx, nil, startTime, startTime.Truncate(time.Hour*24).Add(time.Hour))
+				if err != nil {
+					t.Fatalf("unable to update daily visits stats: %v", err)
+				}
+			}
+			gotStats, _, err := statsDB.UserStatistics(ctx, nil)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			wantStats := &types.UserStatistics{
+				RegisteredUsersByType: map[string]int64{
+					"native":  3,
+					"bridged": 1,
+				},
+				R30Users: map[string]int64{
+					"all":      2,
+					"android":  1,
+					"electron": 1,
+				},
+				R30UsersV2: map[string]int64{
+					"ios":      0,
+					"android":  1,
+					"web":      1,
+					"electron": 0,
+					"all":      2,
+				},
+				AllUsers:        6,
+				NonBridgedUsers: 5,
+				DailyUsers:      3,
+				MonthlyUsers:    5,
+			}
+			if !reflect.DeepEqual(gotStats, wantStats) {
+				t.Errorf("UserStatistics() gotStats = \n%+v\nwant\n%+v", gotStats, wantStats)
+			}
+		})
+	})
+
+}
diff --git a/userapi/types/statistics.go b/userapi/types/statistics.go
new file mode 100644
index 00000000..09564f78
--- /dev/null
+++ b/userapi/types/statistics.go
@@ -0,0 +1,30 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package types
+
+type UserStatistics struct {
+	RegisteredUsersByType map[string]int64
+	R30Users              map[string]int64
+	R30UsersV2            map[string]int64
+	AllUsers              int64
+	NonBridgedUsers       int64
+	DailyUsers            int64
+	MonthlyUsers          int64
+}
+
+type DatabaseEngine struct {
+	Engine  string
+	Version string
+}
diff --git a/userapi/userapi.go b/userapi/userapi.go
index 9174119e..5b11665d 100644
--- a/userapi/userapi.go
+++ b/userapi/userapi.go
@@ -30,6 +30,7 @@ import (
 	"github.com/matrix-org/dendrite/userapi/inthttp"
 	"github.com/matrix-org/dendrite/userapi/producers"
 	"github.com/matrix-org/dendrite/userapi/storage"
+	"github.com/matrix-org/dendrite/userapi/util"
 	"github.com/sirupsen/logrus"
 )
 
@@ -104,5 +105,9 @@ func NewInternalAPI(
 	}
 	time.AfterFunc(time.Minute, cleanOldNotifs)
 
+	if base.Cfg.Global.ReportStats.Enabled {
+		go util.StartPhoneHomeCollector(time.Now(), base.Cfg, db)
+	}
+
 	return userAPI
 }
diff --git a/userapi/util/phonehomestats.go b/userapi/util/phonehomestats.go
new file mode 100644
index 00000000..ad93a50e
--- /dev/null
+++ b/userapi/util/phonehomestats.go
@@ -0,0 +1,160 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package util
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"math"
+	"net/http"
+	"runtime"
+	"syscall"
+	"time"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/userapi/storage"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/sirupsen/logrus"
+)
+
+type phoneHomeStats struct {
+	prevData   timestampToRUUsage
+	stats      map[string]interface{}
+	serverName gomatrixserverlib.ServerName
+	startTime  time.Time
+	cfg        *config.Dendrite
+	db         storage.Statistics
+	isMonolith bool
+	client     *http.Client
+}
+
+type timestampToRUUsage struct {
+	timestamp int64
+	usage     syscall.Rusage
+}
+
+func StartPhoneHomeCollector(startTime time.Time, cfg *config.Dendrite, statsDB storage.Statistics) {
+
+	p := phoneHomeStats{
+		startTime:  startTime,
+		serverName: cfg.Global.ServerName,
+		cfg:        cfg,
+		db:         statsDB,
+		isMonolith: cfg.IsMonolith,
+		client: &http.Client{
+			Timeout:   time.Second * 30,
+			Transport: http.DefaultTransport,
+		},
+	}
+
+	// start initial run after 5min
+	time.AfterFunc(time.Minute*5, p.collect)
+
+	// run every 3 hours
+	ticker := time.NewTicker(time.Hour * 3)
+	for range ticker.C {
+		p.collect()
+	}
+}
+
+func (p *phoneHomeStats) collect() {
+	p.stats = make(map[string]interface{})
+	// general information
+	p.stats["homeserver"] = p.serverName
+	p.stats["monolith"] = p.isMonolith
+	p.stats["version"] = internal.VersionString()
+	p.stats["timestamp"] = time.Now().Unix()
+	p.stats["go_version"] = runtime.Version()
+	p.stats["go_arch"] = runtime.GOARCH
+	p.stats["go_os"] = runtime.GOOS
+	p.stats["num_cpu"] = runtime.NumCPU()
+	p.stats["num_go_routine"] = runtime.NumGoroutine()
+	p.stats["uptime_seconds"] = math.Floor(time.Since(p.startTime).Seconds())
+
+	ctx, cancel := context.WithTimeout(context.TODO(), time.Minute*1)
+	defer cancel()
+
+	// cpu and memory usage information
+	err := getMemoryStats(p)
+	if err != nil {
+		logrus.WithError(err).Warn("unable to get memory/cpu stats, using defaults")
+	}
+
+	// configuration information
+	p.stats["federation_disabled"] = p.cfg.Global.DisableFederation
+	p.stats["nats_embedded"] = true
+	p.stats["nats_in_memory"] = p.cfg.Global.JetStream.InMemory
+	if len(p.cfg.Global.JetStream.Addresses) > 0 {
+		p.stats["nats_embedded"] = false
+		p.stats["nats_in_memory"] = false // probably
+	}
+	if len(p.cfg.Logging) > 0 {
+		p.stats["log_level"] = p.cfg.Logging[0].Level
+	} else {
+		p.stats["log_level"] = "info"
+	}
+
+	// message and room stats
+	// TODO: Find a solution to actually set these values
+	p.stats["total_room_count"] = 0
+	p.stats["daily_messages"] = 0
+	p.stats["daily_sent_messages"] = 0
+	p.stats["daily_e2ee_messages"] = 0
+	p.stats["daily_sent_e2ee_messages"] = 0
+
+	// user stats and DB engine
+	userStats, db, err := p.db.UserStatistics(ctx)
+	if err != nil {
+		logrus.WithError(err).Warn("unable to query userstats, using default values")
+	}
+	p.stats["database_engine"] = db.Engine
+	p.stats["database_server_version"] = db.Version
+	p.stats["total_users"] = userStats.AllUsers
+	p.stats["total_nonbridged_users"] = userStats.NonBridgedUsers
+	p.stats["daily_active_users"] = userStats.DailyUsers
+	p.stats["monthly_active_users"] = userStats.MonthlyUsers
+	for t, c := range userStats.RegisteredUsersByType {
+		p.stats["daily_user_type_"+t] = c
+	}
+	for t, c := range userStats.R30Users {
+		p.stats["r30_users_"+t] = c
+	}
+	for t, c := range userStats.R30UsersV2 {
+		p.stats["r30v2_users_"+t] = c
+	}
+
+	output := bytes.Buffer{}
+	if err = json.NewEncoder(&output).Encode(p.stats); err != nil {
+		logrus.WithError(err).Error("unable to encode anonymous stats")
+		return
+	}
+
+	logrus.Infof("Reporting stats to %s: %s", p.cfg.Global.ReportStats.Endpoint, output.String())
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodPost, p.cfg.Global.ReportStats.Endpoint, &output)
+	if err != nil {
+		logrus.WithError(err).Error("unable to create anonymous stats request")
+		return
+	}
+	request.Header.Set("User-Agent", "Dendrite/"+internal.VersionString())
+
+	_, err = p.client.Do(request)
+	if err != nil {
+		logrus.WithError(err).Error("unable to send anonymous stats")
+		return
+	}
+}
diff --git a/userapi/util/stats.go b/userapi/util/stats.go
new file mode 100644
index 00000000..22ef12aa
--- /dev/null
+++ b/userapi/util/stats.go
@@ -0,0 +1,47 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !wasm && !windows
+// +build !wasm,!windows
+
+package util
+
+import (
+	"syscall"
+	"time"
+
+	"github.com/sirupsen/logrus"
+)
+
+func getMemoryStats(p *phoneHomeStats) error {
+	oldUsage := p.prevData
+	newUsage := syscall.Rusage{}
+	if err := syscall.Getrusage(syscall.RUSAGE_SELF, &newUsage); err != nil {
+		logrus.WithError(err).Error("unable to get usage")
+		return err
+	}
+	newData := timestampToRUUsage{timestamp: time.Now().Unix(), usage: newUsage}
+	p.prevData = newData
+
+	usedCPUTime := (newUsage.Utime.Sec + newUsage.Stime.Sec) - (oldUsage.usage.Utime.Sec + oldUsage.usage.Stime.Sec)
+
+	if usedCPUTime == 0 || newData.timestamp == oldUsage.timestamp {
+		p.stats["cpu_average"] = 0
+	} else {
+		// conversion to int64 required for GOARCH=386
+		p.stats["cpu_average"] = int64(usedCPUTime) / (newData.timestamp - oldUsage.timestamp) * 100
+	}
+	p.stats["memory_rss"] = newUsage.Maxrss
+	return nil
+}
diff --git a/userapi/util/stats_wasm.go b/userapi/util/stats_wasm.go
new file mode 100644
index 00000000..a182e4e6
--- /dev/null
+++ b/userapi/util/stats_wasm.go
@@ -0,0 +1,20 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package util
+
+// stub, since WASM doesn't support syscall.Getrusage
+func getMemoryStats(p *phoneHomeStats) error {
+	return nil
+}
diff --git a/userapi/util/stats_windows.go b/userapi/util/stats_windows.go
new file mode 100644
index 00000000..0b3f8d01
--- /dev/null
+++ b/userapi/util/stats_windows.go
@@ -0,0 +1,29 @@
+// Copyright 2022 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !wasm
+// +build !wasm
+
+package util
+
+import (
+	"runtime"
+)
+
+func getMemoryStats(p *phoneHomeStats) error {
+	var memStats runtime.MemStats
+	runtime.ReadMemStats(&memStats)
+	p.stats["memory_rss"] = memStats.Alloc
+	return nil
+}