Build Local API Mocks with Mockoon (No Code)
A mock running in under a minute, no server required
Prerequisites
- Mockoon desktop app
Steps
Create an environment
Open Mockoon and add a new environment.
Add a route
Click a route, set the method and endpoint, and add a sample response.
Run it
Start the environment; Mockoon serves it on a local port.
Verify
Calling the local port returns your sample response — no backend required.
Mockoon’s whole pitch is speed: no DSL, no server, just clicks. It is the fastest way to unblock frontend work while the real API is still in progress.
Why this matters: frontend developers lose days waiting on backend endpoints that don’t exist yet. A local mock that takes a minute to build keeps them moving, and because Mockoon runs on a real local port, the integration is indistinguishable from the real thing from the browser’s point of view.
Troubleshooting tip: if the frontend can’t reach the mock, check that the environment is actually running and that the route’s method and path match the request exactly — Mockoon matches on both, and a trailing slash or wrong verb returns nothing.
What you’ll have when you finish
You’ll have a Mockoon environment serving a sample response on a local port, with zero backend and zero code. From the browser or a fetch call, the mock is indistinguishable from the real thing, so frontend work proceeds while the API is still being built.
The environment file is the artifact to keep. Commit it and a teammate opens the exact same mock; that’s how small teams share a double without standing up a server.
Troubleshooting
If the frontend gets nothing back, check the environment is actually running and that the route’s method and path match the request exactly. Mockoon matches on both, and a trailing slash or wrong verb returns an empty response rather than an error, which looks like a mystery.
If the response is wrong, not missing, check the response rules. A rule keyed on a header or body field can silently override your default response; confirm the rule conditions match what the client actually sends.
If the port is taken, change it in the environment settings. Mockoon binds a local port, and a conflict with another app just means picking a free one.
Variations
Add response rules so one route returns different payloads based on a query param or header — useful for mocking "logged in versus anonymous" from a single endpoint.
Export the environment and serve it with the Mockoon CLI for a small team’s shared mock, or hand the GUI mock to a designer who can edit responses without touching code. The CLI is the bridge from local spike to something a team can call together.