Setting up a dev environment

Swagger UI includes a development server that provides hot module reloading and unminified stack traces, for easier development.


  • git, any version
  • Node.js >=20.3.0 and npm >=9.6.7 are the minimum required versions that this repo runs on, but we always recommend using the latest version of Node.js.


  1. git clone
  2. cd swagger-ui
  3. npm install
  4. npm run dev
  5. Wait a bit
  6. Open http://localhost:3200/

Using your own local api definition with local dev build

You can specify a local file in dev-helpers/dev-helper-initializer.js by changing the url parameter. This local file MUST be located in the dev-helpers directory or a subdirectory. As a convenience and best practice, we recommend that you create a subdirectory, dev-helpers/examples, which is already specified in .gitignore.


url: "",


url: "./examples/your-local-api-definition.yaml",

Files in dev-helpers should NOT be committed to git. The exception is if you are fixing something in index.html, oauth2-redirect.html, dev-helper-initializer.js, or introducing a new support file.

Bonus points

  • Swagger UI includes an ESLint rule definition. If you use a graphical editor, consider installing an ESLint plugin, which will point out syntax and style errors for you as you code.
    • The linter runs as part of the PR test sequence, so don't think you can get away with not paying attention to it!