Start from the catalog

Updated Aug 30, 2026·3 min read

The catalog is a curated set of provider APIs: the specs teams ask for most, prepared so a working mock is one click away. Stripe, Twilio, Adyen and more, each with a description, tags and a version to pick.

Browse it

Open Simulations, click the arrow next to New simulation and pick Browse catalog. Search by name or tag, or filter by category.

The catalog

The catalog grows by request: if the API you need is not in it, contact us and we will look at adding it.

What a spec ships

The info button on a card opens the details:

Spec details, here for the Stripe mock
  • Version is the build of the mock you get. Some specs keep several; pick one on the card, or take the latest.
  • Endpoints (active / total) is what the mock serves out of the provider's full API. Some specs are trimmed on purpose: the Stripe mock keeps the checkout flow and leaves the rest out, so it stays small and fast.
  • Links point at the provider's own documentation and terms.

Specs differ in what they need to run. A heavy one carries a recommended memory and timeout, and the import compares them against your plan.

A spec can recommend more memory or a longer timeout than your plan provides. You can still import it, and the import says so; calls may time out or be killed if the spec needs more than the plan gives.

From catalog to running mock

Click Add on a card. A simulation is created for you, named automatically, with the spec attached; it opens ready to deploy.

Inside an existing simulation the same catalog sits under Sources. There Add to simulation attaches the spec to that simulation instead, on a mount path you pick; the dialog previews the URL the spec will answer on. One simulation can serve several providers side by side this way.

Adding a catalog spec to an existing simulation

Then deploy as usual.

See Deploy and URLs.

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