Mock Service Worker vs Mockfly
Mock Service Worker
mswjs.ioMockfly
mockfly.devSide by side
| Figure | Mock Service Worker | Mockfly |
|---|---|---|
| Price from | — | €12.50/mo |
| Free plan | — | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Linux | — | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 0 | 7 |
| Spec score · API Mocking Tools | 7.1 (#21) | 9.2 (#2) |
| Purpose | Mock Service Worker (MSW) is an API mocking library for browser and Node.js that intercepts outgoing requests so developers can observe and respond with mocked responses. | Mockfly creates hosted mock REST API endpoints so teams can build and test before a backend is ready. |
| Support | The quick start directs users to a debugging runbook, MSW Discord, and GitHub Discussions for help. | Support is provided directly by the builders through email, in English or Spanish. |
| What it does | MSW is an API mocking library for browser and Node.js that intercepts outgoing requests so they can be observed and answered with mocked responses. | Mockfly provides hosted HTTPS mock API endpoints so teams can build and test before a real backend exists. |
Plans
Mockfly
- StarterFree
- StarterFree
- Pro€15 a month
- Team€49 a month
- Pro annual€150 a year
- Company€199 a month
- CompanyPriced on request
In their own words
Mock Service Worker
Mock Service Worker has no write-up on Specifiction yet; its figures are above.
Mockfly
Mockfly provides hosted mock REST API endpoints for teams building or testing before a backend is ready. An endpoint can return JSON, XML, or files such as PDFs and CSVs, and can select among several responses using rules tied to incoming requests. Mock data can use Faker.js templates or AI-generated JSON. Projects can start from OpenAPI, Swagger, Postman collection, or HAR imports; a Chrome extension can capture browser requests and add selected endpoints. Teams can share and edit mocks, inspect request logs, and review response-body history. For offline work, the mockfly-cli npm package pulls projects to serve locally. A public REST API and MCP server support programmatic mock creation and editing. Mockfly lists API, extension, Linux, self-hosted, and web platforms, and supports REST and WebSocket. The free Starter plan allows 500 requests per day, one project, four endpoints, and two responses per endpoint. Pro costs €15 a month; Team costs €49 a month; Company is listed from €199 a month.