Reference docs

Working locally


Begin has full support for local, offline development, including support for Begin Data.

After you've initialized your project locally, Begin's open core, Architect kicks up a local server that emulates key serverless services (such as Lambda, API Gateway, DynamoDB, etc.).

Those workflows enable you to locally:

  • Preview - run your code locally, to be opened in a web browser, curl, etc.
  • Test - run your code headlessly in a terminal

This guide is an expanded reference to much of what we covered in the quickstart if you'd like to skip ahead.

Getting set up

Get started working locally on your app in five easy steps. Assuming you used the default name of Begin app, open your terminal app, and:

  1. Clone your app's repo to your local machine:
    git clone{your GH username}/begin-app.git
  • cd to your Begin project directory:

    cd begin-app
  • Install NPM packages:

    npm install
  • Hydrate your app's dependencies:

    npx hydrate
  • Start the app locally:

    npm start

That's it, you're up and running locally!

Previewing changes

All changes to your application's business logic within a Function directory (e.g. src/http/get-hello-world) will be immediately available without requiring a restart.

However, changes to shared code in src/shared/ or src/views/ do require a local server restart. For this, a tool like nodemon can be helpful.

Here's an example nodemon config to add to your package.json:

"scripts": {
  "start": "nodemon --exec NODE_ENV=testing ARC_LOCAL=1 npx sandbox",
"nodemonConfig": {
  "watch": [
  "ext": "css,js,json,md,mjs"

Working with routes

The Begin web UI is (currently) responsible for creating new HTTP routes. (A command line interface is in the works, though!)

To create new a new HTTP route: open Begin, click the Functions view in the left nav, then click Add a Function, and select your HTTP method and path.

New routes will be automatically committed to your project; run git pull && npx hydrate to continue working locally with your new routes.

✨ Tip: npx hydrate is a helpful Begin tool to learn; it traverses your routes (e.g. src/http/**) and shared code (src/shared, src/views), finds any package.json files, and (re)installs your modules.

Writing tests

Begin apps come provisioned with tape and some boilerplate tests in the test directory.

  "scripts": {
    "test": "NODE_ENV=testing tape test/*-test.js | tap-spec"

While you can use any test runner and reporter combo you want, the TAP family is strongly recommended; test suites that require test runners to inject globals create difficult-to-debug situations.

⚠️ Begin requires NODE_ENV=testing to be present in your npm test scripts, regardless of the test framework you're using.