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Boxel Runtime

For a quickstart, see here


  • you will want the Glint vscode extension
  • you will want the vscode-glimmer vscode extension
  • you will want the Playwright vscode extension
  • this project uses volta for Javascript toolchain version management. Make sure you have the latest verison of volta on your system and have define the ENV var described here.
  • this project uses pnpm for package management. run pnpm install to install the project dependencies first.
  • this project uses docker. Make sure to install docker on your system.


packages/host is the card runtime host application

packages/realm-server is a node app that serves the realm as an HTTP server, as well as, it can also host the runtime application for its own realm.

packages/boxel-ui/addon is the UI components Ember addon

packages/boxel-ui/test-app is the test suite and component explorer for boxel-ui, deployed at

packages/boxel-motion/addon is the animation primitives ember addon.

packages/boxel-motion/test-app is the demo app for boxel-motion, deployed at

packages/matrix is the docker container for running the matrix server: synapse, as well as tests that involve running a matrix client.

packages/ai-bot is a node app that runs a matrix client session and an OpenAI session. Matrix message queries sent to the AI bot are packaged with an OpenAI system prompt and operator mode context and sent to OpenAI. The ai bot enriches the OpenAI response and posts the response back into the matrix room.

To learn more about Boxel and Cards, see our documentation

Running the Host App

There exists a "dev" mode in which we can use ember-cli to host the card runtime host application which includes live reloads. Additionally, you can also use the realm server to host the app, which is how it will be served in production.

ember-cli Hosted App

Prerequisite: Make sure that you have created a matrix user for the base realm, drafts realm, and for the published realm. To make it easier, you can execute pnpm register-realm-users in packages/matrix/, this will create a matrix user for the base realm, drafts realm, and a matrix user for the published realm.

In order to run the ember-cli hosted app:

  1. pnpm build in the boxel-ui/addon workspace to build the boxel-ui addon.
  2. pnpm build in the boxel-motion/addon workspace to build the boxel-motion addon.
  3. pnpm start in the host/ workspace to serve the ember app. Note that this script includes the environment variable OWN_REALM_URL=http://localhost:4201/draft/ which configures the host to point to the draft realm's cards realm by default.
  4. pnpm start:all in the realm-server/ to serve the base realm, draft realm and published realm -- this will also allow you to switch between the app and the tests without having to restart servers)

The app is available at http://localhost:4200. It will serve the draft realm (configurable with OWN_REALM_URL, as mentioned above). You can open the base and draft cards workspace directly by entering http://localhost:4201/base or http://localhost:4201/draft in the browser (and additionally the published realm by entering http://localhost:4201/published).

If you want to use operator mode, you need to register an account on Matrix. To make it easier, you can execute pnpm register-test-user in packages/matrix/. Now you can sign in with the test user using the credentials username: user, password: password.

When you are done running the app you can stop the synapse server by running the following from the packages/matrix workspace:

pnpm stop:synapse

Realm server Hosted App

In order to run the realm server hosted app:

  1. pnpm start:build in the host/ workspace to re-build the host app (this step can be omitted if you do not want host app re-builds)
  2. pnpm start:all in the realm-server/ to serve the base, draft, and published realms

You can visit the URL of each realm server to view that realm's app. So for instance, the base realm's app is available at http://localhost:4201/base and the draft realm's app is at http://localhost:4201/draft.

Live reloads are not available in this mode, but you can just refresh the page to grab the latest code changes if you are running rebuilds (step #1 and #2 above).

Using start:all

Instead of running pnpm start:base, you can alternatively use pnpm start:all which also serves a few other realms on other ports--this is convenient if you wish to switch between the app and the tests without having to restart servers. Here's what is spun up with start:all:

Port Description Running start:all Running start:base
:4201 /base base realm
:4201 /drafts draft realm 🚫
:4201 /published draft realm 🚫
:4202 /test host test realm, /node-test node test realm 🚫
:4203 root (/) base realm 🚫
:4204 root (/) drafts realm 🚫
:4205 qunit server mounting realms in iframes for testing 🚫
:5001 Mail user interface for viewing emails sent to local SMTP 🚫
:5435 Postgres DB 🚫
:8008 Matrix synapse server 🚫

Using start:development

You can also use start:development if you want the functionality of start:all, but without running the test realms. start:development will enable you to open http://localhost:4201 and allow to select between the cards in the /base and /drafts realm.

Card Pre-rendering

In order to support server-side rendered cards, this project incorporates FastBoot. By default pnpm start in the packages/host workspace will serve server-side rendered cards. Specifically, the route /render?url=card_url&format=isolated will serve pre-rendered cards. There is additional build overhead required to serve pre-rendered cards. If you are not working on the /render route in the host, then you would likely benefit from disabling FastBoot when starting up the host server so that you can have faster rebuilds. To do so, you can start the host server using: FASTBOOT_DISABLED=true pnpm start.

The realm server also uses FastBoot to pre-render card html. The realm server boots up the host app in a FastBoot container. The realm server will automatically look for the host app's dist/ output to use when booting up the infrastructure for pre-rendering cards. Make sure to start to the host app first before starting the realm server so that the host app's dist/ output will be generated. If you are making changes that effect the /render route in the host app, you'll want to restart the host app (or run pnpm build) in order for the realm server to pick up your changes.

Request Accept Header

The realm server uses the request accept header to determine the type of request being made and in what format it should return the content.

Accept Header URL rules Description
application/vnd.card+json If card instance URL includes the .json extension, the server will redirect to the URL without the extension. Used to request card instances for normal consumption
application/vnd.card+source For code modules we support node-like resolution, which means that the extension is optional. If the extension is not provided the server will redirect to the URL with the extension. We also support card instance requests without the .json extension. The server will redirect to the URL with the extension. Used to request source file format for code modules or card instances (note that card instances are returned using file serialization which notably contains no id property)
application/vnd.api+json Directory listing requests need to have their URL's end with a / character Used to request a directory listing or to get realm info
text/event-stream only <REALM_URL>/_messages is supported Used to subscribe to realm events via Server Sent Events
text/html Card instance URL's should not include the .json file extension. This is considered a 404 Used to request rendered card instance html (this serves the host application)
*/* We support node-like resolution, which means that the extension is optional Used to request transpiled executable code modules


Boxel uses a Postgres database. In development, the Postgres database runs within a docker container, boxel-pg, that is started as part of pnpm start:all. You can manually start and stop the boxel-pg docker container using pnpm start:pg and pnpm stop:pg. The postgres database runs on port 5435 so that it doesn't conflict with a natively installed postgres that may be running on your system.

When running tests we isolate the database between each test run by actually creating a new database for each test with a random database name (e.g. test_db_1234567). The test databases are dropped before the beginning of each test run.

If you wish to drop the development databases you can execute:

pnpm drop-all-dbs

You can then run pnpm migrate up (with PGDATABASE set accordingly if you want to migrate a database other than boxel) or just start the realm server (pnpm start:all) to create the database again.

To interact with your local database directly you can use psql:

psql -h localhost -p 5435 -U postgres

DB Migrations

When the realm server starts up it will automatically run DB migrations that live in the packages/realm-server/migrations folder. As part of development you may wish to run migrations manually as well as to create a new migration.

To create a new migration, from packages/realm-server, execute:

pnpm migrate create name-of-migration

This creates a new migration file in packages/realm-server/migrations. You can then edit the newly created migration file with the details of your migration. We use node-pg-migrate to handle our migrations. You can find the API at

To run the migration, execute:

pnpm migrate up

To revert the migration, execute:

pnpm migrate down

Boxel also uses SQLite in order to run the DB in the browser as part of running browser tests (and eventually we may run the realm server in the browser to provide a local index). We treat the Postgres database schema as the source of truth and derive the SQLite schema from it. Therefore, once you author and apply a migration, you should generate a new schema SQL file for SQLite. To generate a new SQLite schema, from packages/realm-server, execute:

pnpm make-schema

This will create a new SQLite schema based on the current postgres DB (the schema file will be placed in the packages/host/config/schema directory). This schema file will share the same timestamp as the latest migration file's timestamp. If you forget to generate a new schema file, the next time you start the host app, you will receive an error that the SQLite schema is out of date.

Matrix Server

The boxel platform leverages a Matrix server called Synapse in order to support identity, workflow, and chat behaviors. This project uses a dockerized Matrix server. We have multiple matrix server configurations (currently one for development that uses a persistent DB, and one for testing that uses an in-memory DB). You can find and configure these matrix servers at packages/matrix/docker/synapse/*.

This server is automatically started as part of the pnpm start:all script, but if you wish to control it separately, from packages/matrix, execute:

pnpm start:synapse

The local Matrix server will be running at http://localhost:8008.

To stop the matrix server, from packages/matrix, execute:

pnpm stop:synapse

Matrix Administration

Matrix administration requires an administrative user and a special client in order to use. Matrix administration is used for creating users, creating rooms, creating registration tokens, managing media, viewing events, etc. Note that you will need to use the matrix administration UI to create tokens to register new matrix users or you can execute pnpm register-test-token and use the token dev-token.

First you must create an administrative user:

  1. start the matrix server pnpm start:synapse
  2. run a script to create an administrative user:
    docker exec -it boxel-synapse register_new_matrix_user http://localhost:8008 -c /data/homeserver.yaml -u admin -p your_admin_password --admin
    Alternatively, you can execute pnpm register-test-admin and utilize the following credentials: user: admin and password: password.

After you have created an administrative user and can start the admin console by executing the following in the packages/matrix workspace:

pnpm start:admin

Then visit http://localhost:8080, and enter the admin user's username (admin) and the password, also enter in your matrix server url http://localhost:8008 in the homeserver URL field, and click "Signin".

Note you can use this same administrative interface to login to the staging and production matrix server. The credentials are available in AWS SSM Parameter Store.

To stop the admin console run the following in the packages/matrix workspace:

pnpm stop:admin

SMTP Server

Matrix requires an SMTP server in order to send emails. In order to facilitate this we leverage smtp4dev in dev and test (CI) environments . This is a docker container that includes both a local SMTP server and hosts a web app for viewing all emails send from the SMTP server (the emails never leave the docker container). smtp4dev runs in the same docker network as synapse, so the SMTP port is never projected to the docker host. smtp4dev also runs the web app used to view emails sent from the SMTP server at http://localhost:5001. You can open a browser tab with this URL to view any emails sent from the matrix server. As well as, our matrix tests leverage the mail web app in order to perform email assertions. smtp4dev is automatically started as part of running pnpm start:all in the packages/realm-server workspace.

Boxel UI Component Explorer

There is a ember-freestyle component explorer available to assist with development. In order to run the freestyle app:

  1. cd packages/boxel-ui/test-app
  2. pnpm start
  3. Visit http://localhost:4210/ in your browser

Boxel Motion Demo App

In order to run the boxel-motion demo app:

  1. cd packages/boxel-motion/test-app
  2. pnpm start
  3. Visit http://localhost:4200 in your browser

Running the Tests

There are currently 5 test suites:


To run the packages/host/ workspace tests start the following servers:

  1. pnpm start:all in the packages/realm-server/ to serve both the base realm and the realm that serves the test cards
  2. pnpm start in the packages/host/ workspace to serve ember

The tests are available at http://localhost:4200/tests

Realm Server Node tests

First make sure to generate the host app's dist/ output in order to support card pre-rendering by first starting the host app (instructions above). If you want to make the host app's dist/ output without starting the host app, you can run pnpm build in the host app's workspace.

To run the packages/realm-server/ workspace tests start:

  1. pnpm start:all in the packages/realm-server/ to serve both the base realm and the realm that serves the test cards for node.
  2. Run pnpm test in the packages/realm-server/ workspace to run the realm node tests

Realm Server DOM tests

This test suite contains acceptance tests for asserting that the Realm server is capable of hosting its own app. To run these tests in the browser execute the following in the packages/realm-server workspace:

  1. pnpm start:all

Visit http://localhost:4205 after the realms have finished starting up

Boxel UI

  1. cd packages/boxel-ui/test-app
  2. pnpm test (or pnpm start and visit http://localhost:4210/tests to run tests in the browser)

Boxel Motion

  1. cd packages/boxel-motion-test-app
  2. pnpm test (or pnpm start and visit http://localhost:4200/tests to run tests in the browser)

Matrix tests

This test suite contains tests that exercise matrix functionality. These tests are located at packages/matrix/tests, and are executed using the Playwright test runner. To run the tests from the command line, first make sure that the matrix server is not already running. You can stop the matrix server by executing the following from packages/matrix

pnpm stop:synapse

The matrix client relies upon the host app and the realm servers. Start the host app from the packages/host folder:

pnpm start

Then start the realm server (minus the matrix server). From the packages/realm-server folder:

pnpm start:without-matrix

Then to run the tests from the CLI execute the following from packages/matrix:

pnpm test

Alternatively you can also run these tests from VS Code using the VS Code Playwright plugin (which is very strongly recommended). From the "test tube" icon, you can click on the play button to run a single test or all the tests.


or click on the play button in the left margin next to the test itself to run a test: Screenshot_20230428_150147

you can additionally set a breakpoint in code, and playwright will break at the breakpoint.