Update #5 - Hello Prism

Today, we are excited to announce a free, standalone version of Prism!

Prism powers the transformation, validation, and mocking features in our API Designer. Over the last several months we have been working on a standalone version, built around OAS (Swagger 2).

It runs on most operating systems, with no dependencies. For example, running a mock version of the canonical Swagger Petstore API, with dynamic responses and request validations, is as simple as:

  1. Download the appropriate binary.
  2. Run ./prism run --mock --list --spec http://petstore.swagger.io/v2/swagger.json in your terminal.
  3. Read more about Prism's capabilities.

Prism includes other useful utilities, to help when working with OAS files, like printing endpoints to terminal, and validating specs.

Please give Prism a try and let us know what you think!

This update also includes numerous improvements to the API designer. Highlights are detailed below.


  • [new] Overhauled StopLight documentation.
  • [new] Significantly improved latency and responsiveness throughout designer.
  • [new] Login with Github.
  • [new] Import specification from URL.
  • [new] Include request body examples in exports.
  • [new] Feedback widget. Tell us how we're doing!
  • [new] Add endpoint group as tag, when exporting.
  • [new] When adding an endpoint, allow you to choose which group to add it under.
  • [new] Add back, forward, reload, and open in browser buttons to app.
  • [new] Add search to code editors (cmd/ctrl + f).
  • [new] Auto-save when stop editing editor section.
  • [new] Support endpoint operation ids.


  • [fix] Support circular $ref in schemas / models.
  • [fix] Safari should not require double click for particular buttons.
  • [fix] JSON schema viewer, display boolean defaults.
  • [fix] JSON schema viewer, support combiners correctly, required correctly.