The 8 best mock API tools in 2026 (free and paid, compared)

Hosted mock servers, desktop apps, libraries and CLI tools all "mock an API", but they solve different problems and charge in very different ways. We compared the eight tools developers actually pick between, on free tier, pricing, hosting, dynamic responses and team features. Updated September 2026.

How we compared them

• Where the mock runs. Hosted URL anyone can call, a desktop app or a library inside your code. This decides who can use the mock.
• Free tier and pricing. What you get for nothing and, above all, whether requests are metered. Per-request pricing is where mock servers get expensive.
• Dynamic responses. Different answers for different requests, realistic data, delays, error scenarios.
• Team features. Shared editing, seats, logs, documentation, imports from OpenAPI or Postman.

Third-party prices are the ones listed on each vendor's site in September 2026; check their pricing pages for the current figures. Yes, we build Mockfly. We have tried to be fair, and every comparison page linked below says where the other tool is the better choice.

1. Mockfly

Best for: frontend, mobile and QA teams that need a shared mock API without running anything.

Mockfly is a hosted mock API generator. Create endpoints in a web UI or import an OpenAPI spec, a Postman collection or a HAR capture, and get a live URL under api.mockfly.dev. Each endpoint has several responses, picked by rules on query params, headers, URL params or body (16 comparators, AND/OR groups). Bodies use Faker.js templates or AI-generated JSON, and can be files or XML. There is proxy mode per endpoint, WebSocket mocking, request logs, auto-generated docs, a Chrome extension, an offline CLI, an MCP server and a public REST API.

Free tier: 500 requests a day, 1 project, 4 endpoints, 2 responses per endpoint. Price: Pro 15€/month (150€/year) with unlimited requests, projects and endpoints; Team 49€/month for 5 seats and 9€ per extra seat; Company from 199€/month with the setup done for you. Watch out: no persisted CRUD data and no request validation against the spec.

2. Mockoon

Best for: individual developers who want a powerful, free mock server on their own machine.

Mockoon is an open-source desktop app with a CLI and Docker image. Routes, rules, Faker templating, proxy mode, CRUD routes with data buckets, OpenAPI import and export. Everything runs locally, so nothing is metered and it works offline. Sharing means committing the environment file or paying for Mockoon Cloud, which adds real-time collaboration, a web UI and cloud deployments.

Free tier: the desktop app and CLI, unlimited. Price: Mockoon Cloud Team listed at $100/month for 5 members, 3 cloud deployments and 100,000 calls/month; Enterprise custom. Watch out: the jump from free to $100 a month once the mock has to be shared. Mockfly vs Mockoon.

3. Postman mock servers

Best for: teams already paying for Postman who need a few static examples served.

Postman turns the saved examples of a collection into a hosted mock. Select examples with the x-mock-response-code header, add variety with dynamic variables, keep everything in the workspace you already use. There is no rules engine on request content and every call is metered.

Free tier: 1,000 mock server calls a month for the workspace. Price: Solo $9/month, Team $19 per user/month, Enterprise $49 per user/month, all billed annually, with higher metered allowances. Watch out: a polling frontend can exhaust the free allowance in a day. Mockfly vs Postman mock server.

4. Beeceptor

Best for: inspecting webhooks and quick one-endpoint mocks.

Beeceptor gives you a subdomain that answers immediately and shows every request in a live console. Rules with templating, proxying, CRUD-style mocks, OpenAPI mocking and a local tunnel. Pricing is per endpoint (subdomain) and per request.

Free tier: 1 public endpoint, 50 requests/day, 3 rules. Price: Individual $10/month (15,000 requests/month), Team $25/month (100,000 requests/month, unlimited members), Scale $99/month (1M+). Watch out: requests are counted per endpoint on every plan. Mockfly vs Beeceptor.

5. WireMock and WireMock Cloud

Best for: Java and Kotlin teams that need deep request matching and stateful scenarios in tests.

WireMock is the open-source standard for HTTP stubbing: URL, header and body matching including JSONPath and XPath, Handlebars templating, stateful scenarios, fault injection, record and playback. It runs embedded in tests or as a standalone server. WireMock Cloud hosts the same engine with a UI.

Free tier: the open-source server, self-hosted; WireMock Cloud Free with 1,000 calls/month, 3 mock APIs and 1 user. Price: WireMock Cloud Enterprise, custom quote. Watch out: stubs are code or JSON, and non-developers cannot change them. Mockfly vs WireMock.

6. MockAPI.io

Best for: a persisted fake CRUD backend for a prototype.

Define a resource schema with Faker generators and MockAPI.io exposes a full CRUD API whose data survives between calls. Very fast for a demo where you need to create and edit real items. Less suited to error scenarios, non-resource endpoints or importing an existing contract.

Free tier: 1 project, 2 resources. Price: $5/month or $35/year for 20 projects and 50 resources. Watch out: responses follow the resource shape, so specific error payloads are hard. Mockfly vs MockAPI.

7. MSW (Mock Service Worker)

Best for: unit, component and integration tests in JavaScript and TypeScript projects.

MSW intercepts requests inside your browser (Service Worker) or Node process and answers from handlers you write in code. No network, no flakiness, versioned with the app, works in Jest, Vitest, Playwright and Storybook. The mock lives where that code runs, so a mobile app, another service or a tester only reaches it if you deploy the handlers as a server with the first-party @mswjs/http-middleware, and every change is still a code change.

Free tier: everything, open source. Price: free. Watch out: not a shared URL unless you host one yourself; pair it with a hosted mock server for everything outside the test runner. Mockfly vs MSW.

8. Stoplight Prism

Best for: design-first teams that want a mock and a validation proxy straight from the OpenAPI spec.

prism mock openapi.yaml serves every path from the examples or schema in the document, validates requests against it and can proxy to the real API reporting contract violations. Open source, runs with Node or Docker. No UI, no hosting, no team features; the spec is the only configuration.

Free tier: everything, open source. Price: free (hosting is on you). Watch out: responses cannot branch on request content and only developers can change them. Mockfly vs Prism.

Side by side

Our recommendation

Use a library (MSW) for tests, a local app (Mockoon) if you work alone, and a hosted mock server when more than one person or platform needs the same mock. Among hosted tools, pick by how you pay: flat per seat (Mockfly) if the frontend will hit the mock all day, metered (Postman, Beeceptor, Mockoon Cloud, WireMock Cloud) if usage is occasional or you already pay for the suite.

Frequently asked questions