MimicAPI

MimicAPI is a developer tool designed to remove backend dependency during frontend development.

In typical workflows, frontend progress slows down when APIs are unavailable or incomplete. Common workarounds such as manually writing mock data or defining endpoints in tools like Postman require constant updates and often fall out of sync with the actual backend.

MimicAPI takes a different approach.

It captures real network traffic directly from the browser. Through a Chrome extension, it records fetch and XHR requests along with their headers, request bodies, responses, status codes, and timing data.

Using this captured data, it generates an OpenAPI 3.0.3 specification automatically. Path parameters are inferred dynamically (for example, /users/42 becomes /users/{userId}), and response structures are converted into JSON schemas without manual input.

The generated specification can be served locally using:

node server/src/index.js serve spec.yaml --port 3001

This starts a local server that replays the captured responses. For endpoints without recorded data, realistic mock values are generated based on the inferred schema.

A dashboard is available at /dashboard, where routes can be inspected, request logs can be monitored in real time, and updated specifications can be imported without restarting the server.

The entire system runs locally. It does not require accounts, API keys, or external services. The Chrome extension has no runtime dependencies, and all server components use permissive open-source licenses.

MimicAPI was developed for FOSS Hack 2026 to streamline frontend workflows and reduce delays caused by backend unavailability.