Mock Service Worker
Mock Service Worker (MSW) is an open-source library for mocking REST, GraphQL, WebSocket, and Server-Sent Events APIs at the network level. It provides setupWorker for browser environments and setupServer for Node.js, with handlers (http, graphql, ws, sse) that allow developers to declare mocked responses without modifying application code.
Documentation
Other Resources
HTTP Handler
https://mswjs.io/docs/network-behavior/rest
GraphQL Handler
https://mswjs.io/docs/network-behavior/graphql
WebSocket Handler
https://mswjs.io/docs/network-behavior/websocket
GitHub
https://github.com/mswjs/msw
Examples
https://github.com/mswjs/examples
NPM
https://www.npmjs.com/package/msw
License
https://github.com/mswjs/msw/blob/main/LICENSE.md