Your backend, before your backend.

Spin up a local HTTP server from any collection. Start building your frontend before the API is deployed — or fake the edge cases your real backend won't reproduce.

Rostyman mock server tab with multiple routes, response bodies, and a Start button — running on localhost

Why this is different

Hosted mock services charge per request and force your mock URL to be public. Rostyman's mock server runs on localhost — no account, no per-request cost, no anyone-on-the-internet can hit it. When you need external access, expose it through a tunnel you control.

Three steps from idea to running server

Define routes

Click + Route. Set method, path, status code, headers, body. JSON body with variables gets a live preview.

Press Start

Server boots on a port you pick. Green dot in the sidebar shows which servers are running.

Point and shoot

Set a {{baseUrl}} env variable to http://localhost:YOUR_PORT and every request in the collection just works.

Built for realistic mocking

Multi-route servers

Define as many routes as you need per mock server. Method + path matching with wildcards and path parameters.

Dynamic variables

Mock-server-scoped variables resolve inside responses. Combine with built-ins like {{$randomInt}} and {{$timestamp}} for realistic data.

Live request log

Every hit is logged instantly — method, path, headers, query string, and body. See exactly what your frontend is sending without touching a real backend.

Per-env mocking

Point the same collection at the mock server or the real API by switching environments. Same requests, different backends.

When mocking earns its keep

Build the frontend before the backend is ready — no more blocking handoffs.

Reproduce that 503 your production backend only returns at 3am on Sundays.

Run your entire test suite against deterministic mock data in CI.

Demo the app to a client without touching real data.

Decouple two teams so they can iterate in parallel on a shared contract.

Simulate slow backends with per-route response delay — test your frontend timeout and loading-state handling.

Have a DB schema but no backend? Generate a mock server from your schema — AI shapes responses from column types and FK relations, companion collection included.

On the roadmap

Mock it free today. Real backends are on the roadmap.

Mocking from your schema works today, free. We're also building a future capability that turns a working mock into a real backend — scaffolding route handlers, DB queries, and response types from your mock routes and database schema, in the framework you choose. The generated code would be entirely yours, with no Rostyman dependency at runtime. This is planned for a later release, not part of v1.0.

Express (Node.js)

FastAPI (Python)

Django REST

Spring Boot

NestJS

Laravel

Stop waiting on the backend team.

Local mocks. Real speed. Zero services to sign up for.

Download Free