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API service

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xBrowserSync is a free tool for syncing browser data between different browsers and devices, built for privacy and anonymity. For full details, see

This repository contains the source code for the REST service API that client applications communicate with. If you'd like to run your own xBrowserSync service on your Node.js web server, follow the installation steps below.

Once configured, you can begin syncing your browser data to your xBrowserSync service, and if you're feeling generous, allow others to sync their data to your service also!

API documentation

The available API methods are documented on the home page of each xBrowserSync service, respective of the version that service is running. For example, you can view the API documentation for the official xBrowserSync service at

Running with Docker

The easiest way to get up and running is by using Docker to run the xBrowserSync API as a container. Docker is a popular container management and imaging platform that allows you to quickly work with containers on Linux and Windows.

Once you have installed Docker you can use the xBrowserSync API Docker image to get a production-ready xBrowserSync service up and running with minimal effort (view the README for more information).

Manual installation

Whilst running in a Docker container is the recommended way to run your xBrowserSync service, you can self-host xBrowserSync instead by performing a manual installation on your own server by installing the two dependencies listed as prerequisites and following the six easy steps below:


1. Clone the xBrowserSync API source repo

$ git clone

2. Install and build xBrowserSync API package

(Use the unsafe-perm flag if you get any permissions issues whilst trying to install):

$ npm install --unsafe-perm

3. Configure MongoDB databases

  1. Run the following commands in the mongo shell:

    (Replace [password] with a cleartext password of your choice)

    use admin
    db.createUser({ user: "xbrowsersyncdb", pwd: "[password]", roles: [ { role: "readWrite", db: "xbrowsersync" }, { role: "readWrite", db: "xbrowsersynctest" } ] })
    use xbrowsersync
    db.newsynclogs.createIndex( { "expiresAt": 1 }, { expireAfterSeconds: 0 } )
    db.newsynclogs.createIndex({ "ipAddress": 1 })
  2. Add the following environment variables to hold xBrowserSync DB account username and password:


    On Windows, open a Command Prompt and type (replacing [password] with the password entered in the mongo shell):

    setx XBROWSERSYNC_DB_USER "xbrowsersyncdb"
    setx XBROWSERSYNC_DB_PWD "[password]"

    On Ubuntu/Debian Linux, open a terminal emulator and type:

    $ pico ~/.profile

    Add the lines (replacing [password] with the password entered in the mongo shell):

    export XBROWSERSYNC_DB_USER=xbrowsersyncdb
    export XBROWSERSYNC_DB_PWD=[password]

    Save and exit, then log out and back in again.

If exposing your service to the public it is recommended you also perform the following steps:

  1. Add a TTL index on bookmarks.lastAccessed to delete syncs that have not been accessed for 3 weeks:

    use xbrowsersync
    db.bookmarks.createIndex( { "lastAccessed": 1 }, { expireAfterSeconds: 21*86400 } )

4. Modify configuration settings

The file config/settings.default.json contains all of the default configuration settings. User configuration values should be stored in config/settings.json and will override the defaults. Should you wish to change any of the configuration settings, copy settings.default.json and rename the copy to settings.json before changing any values as required. Be sure to remove any settings that have not been changed so that any amendments to the default values in future versions are picked up. For example, a basic user configuration to modify the service status message could look like:

  "status": {
    "message": "Welcome to my xBrowserSync service!"

Any changes to the user configuration will require the service to be restarted before being picked up. The available configuration settings are:

Config Setting Description Default Value
allowedOrigins Array of origins permitted to access the service. Each origin can be a String or a RegExp. For example [ '', /\.example2\.com$/ ] will accept any request from or from a subdomain of If the array is empty, all origins are permitted [] (All origins permitted)
dailyNewSyncsLimit The maximum number of new syncs that a user can create per day - helps to prevent abuse of the service. If this setting is enabled, IP addresses are added to newsynclogs collection to track usage which is cleared down each day. Set as 0 to disable (allows users to create as many syncs as they want). 3
db.authSource The database to use for authentication. admin
db.connTimeout The connection timeout period to use for MongoDB. Using a high value helps prevent dropped connections in a hosted environment. 30000 (30 secs) The MongoDB server address to connect to, either a hostname, IP address, or UNIX domain socket. Name of the MongoDB database to use. xbrowsersync
db.ssl Connect to MongoDB over SSL. false
db.useSRV Use MongoDB's DNS Seedlist Connection Format to connect to the database. If set to true, should also be set to the relevant DNS hostname. false
db.username Username of the account used to access MongoDB. Set as empty string to use environment variable XBROWSERSYNC_DB_USER. (Empty string, defers to environment variable)
db.password Password of the account used to access MongoDB. Set as empty string to use environment variable XBROWSERSYNC_DB_PWD. (Empty string, defers to environment variable)
db.port The port to use to connect to MongoDB. 27017
location The geographic location of the service, determined by an ISO 3166-1-alpha-2 code. Helps users determine if the service is geographically suitable for them when exposing the service to the public. gb
log.file.enabled If set to true, Bunyan will be used to capture minimal logging (service start/stop, new sync created, errors) to file. Logged messages are output to log.file.path and the log file is rotated automatically each period set by log.file.rotationPeriod, resulting in files "log.file.path.0", "log.file.path.1", etc. true
log.file.level Bunyan log level to capture: trace, debug, info, warn, error, fatal. info
log.file.path File path to log messages to (ensure the account node is running as has permission to write to this location). /var/log/xBrowserSync/api.log
log.file.rotatedFilesToKeep Maximum number of rotated log files to retain. 5
log.file.rotationPeriod The period at which to rotate log files. This is a string of the format "$number$scope" where "$scope" is one of "ms" (milliseconds -- only useful for testing), "h" (hours), "d" (days), "w" (weeks), "m" (months), "y" (years). Or one of the following names can be used "hourly" (means 1h), "daily" (1d), "weekly" (1w), "monthly" (1m), "yearly" (1y). Rotation is done at the start of the scope: top of the hour (h), midnight (d), start of Sunday (w), start of the 1st of the month (m), start of Jan 1st (y). 1d
log.stdout.enabled If set to true, Bunyan will be used to capture minimal logging (service start/stop, new sync created, errors) to stdout. true
log.stdout.level Bunyan log level to capture: trace, debug, info, warn, error, fatal. info
maxSyncs The maximum number of unique syncs to be stored on the service, once this limit is reached no more new syncs are permitted. Users with an existing sync ID are able to get and update their sync data as normal. This value multiplied by the maxSyncSize will determine the maximum amount of disk space used by the xBrowserSync service. Set as 0 to disable. 5242
maxSyncSize The maximum sync size in bytes. Note this is not equivalent to the size/amount of bookmarks as data is compressed and encrypted client-side before being sent to the service. 512000 (500kb)
server.behindProxy Set to true if service is behind a proxy, client IP address will be set from X-Forwarded-For header. Important: Do not set to true unless a proxy is present otherwise client IP address can easily be spoofed by malicious users. false Host name or IP address to use for Node.js server for accepting incoming connections.
server.https.certPath Path to a valid SSL certificate. Required when HTTPS is enabled. (Empty string, no path set)
server.https.enabled If enabled, the service is started using HTTPS. false
server.https.keyPath Path to the SSL certificate's private key. Required when HTTPS is enabled. (Empty string, no path set)
server.port Port to use for Node.js server for accepting incoming connections. 8080
server.relativePath Relative path from the host where the service will be located. Should always begin (and end) with /. /
status.allowNewSyncs Determines whether users will be allowed to create new syncs. Note: if this setting is set to false, users who have already synced to this service and have a sync ID will still able to get and update their syncs. true
status.message This message will be displayed in the service status panel of the client app when using this xBrowserSync service. Ideally the message should be 130 characters or less. Supports markdown formatting. (Empty string, no message set) If set to false no clients will be able to connect to this service. true
tests.db Name of the MongoDB database to use for e2e tests. xbrowsersynctest
tests.port Port to use for running tests. 8081
throttle.maxRequests Max number of connections during throttle.timeWindow milliseconds before sending a 429 response. Set as 0 to disable. 1000
throttle.timeWindow Amount of time (in milliseconds) before throttle counter is reset. 300000 (5 mins)

5. Create log folder

Ensure that the path set in the log.path config value exists, and that the account node will be running as can write to that location.

6. Run xBrowserSync service

$ node dist/api.js


If you've made code changes you can run a fresh build with the command:

$ npm run build


The project includes unit, integration and end to end tests.

To run end to end tests, you will need to create the test database first. Run the following commands in the mongo shell:

(Replace [dbname] with your xBrowserSync database name and [password] with the xBrowserSync database user account password)

use [dbname]test
db.createUser({ user: "xbrowsersyncdb", pwd: "[password]", roles: ["readWrite"] })

You can then run the end to end tests by running the following command:

$ npm run test

Upgrading from an earlier version

<= v1.1.5

From v1.1.6, database users are created in the admin database. When upgrading from an earlier version you'll either need to drop the existing users in the xbrowsersync database and recreate them in the admin database, or simply add the following to your config/settings.json file:

"db": {
  "authSource": "xbrowsersync"

Config settings for logging has also changed so ensure you update your config/settings.json file if you have customised logging settings.

<= v1.0.3

If you are curently running v1.0.3 (or earlier) of the xBrowserSync API, you will need to export existing syncs and delete the xBrowserSync database before upgrading.

To export existing syncs, run the following command:

mongoexport --db xBrowserSync -c bookmarks --out /path/to/export/file

Then to delete the database, run the following commands in the mongo shell:

use xBrowserSync

Once you've upgraded and completed the installation steps below, you can import the syncs by running the following command:

mongoimport --db xbrowsersync -c bookmarks --file /path/to/export/file

Other Implementations

Google Cloud

Cloudflare Worker

VS Code

If you're using VS Code, you have the following launch configurations:

  1. Debug API: Will compile and debug the main API service.
  2. Debug docs: Will launch API home page in chrome and attach to debugger for debugging docs issues.
  3. Run unit/integration tests: Will debug tests in *.spec.ts files in src folder.
  4. Run e2e tests: Will debug tests in test/e2e folder.

Note: we recommend VSCodium for running VSCode without Microsoft's proprietary binaries and telemetry/tracking.

Issues and feature requests

Please log Docker-related issues in the api-docker Issues list, if you have found an issue with the xBrowserSync API itself or wish to request a new feature, do so in the api Issues list.