← Back to Builder

Running locally

The builder is a static site — plain HTML, CSS and vanilla-JS ES modules. There is no build step and no backend. You only need a local HTTP server, because ES modules are blocked over the file:// protocol.

Prerequisites

  • Node.js — used only to run a static file server and the tests. Any recent LTS works.
  • A modern browser (Chromium, Firefox or Safari).

No compilation, bundler or framework install is required to use the app.

Start the app

From the repository root, serve the folder over HTTP and open it in a browser:

npx serve .
# then open http://localhost:3000

On Windows you can use the bundled helper instead:

.\start.ps1

Either way, the app boots from index.html. It loads a sample questionnaire by default so you have something to explore immediately.

Why a server? Opening index.html directly with file:// fails — the browser refuses to load ES modules from the file system. Always go through http://localhost:....

Running the tests

Unit tests run in Vitest, end-to-end tests in Playwright (Chromium):

npm test             # unit tests — single run
npm run test:watch   # unit tests — watch mode
npm run test:e2e     # end-to-end tests
npm run test:e2e:ui  # end-to-end tests — Playwright UI

Linting uses ESLint:

npm run lint

Vitest and Playwright also run automatically in CI on every push.

Hosted version

If you just want to try it without cloning anything, the same site is deployed to GitHub Pages at https://fhirbuilder.com/.

Next: Quick tour walks through the interface, or jump into Core concepts.