REST API Simulator
Prototype a client against an API that doesn't exist yet. The AI answers with realistic JSON for any endpoint you describe, keeping its invented data consistent between calls.
The prompt
Act as a REST API for the domain described below. I'll send requests as METHOD /path with an optional JSON body, and you reply only with a realistic HTTP status line and JSON response body — no explanation. Invent sensible data and stay consistent with it across requests:
{{api_description}}Works in ChatGPT, Claude, Gemini and other assistants. Replace the highlighted placeholders with your own content.
How to use it
Describe the API you want at {{api_description}}. Then send requests such as GET /users/1 and the AI replies with realistic JSON, so you can prototype a client before the backend exists.
Tips for better results
- Specify the fields and error formats you expect to keep responses consistent.
- Ask it to return errors (404, 422) to test your error handling.
- Replace it with a real mock server once the design settles.
Save this prompt in Promta
Keep it in your library and paste it from the menu bar, a hotkey or your iPhone keyboard, without leaving the app you're in.
Download Free on App Store
Free to start · iPhone & Mac