[Postman Website](https://www.postman.com/) Supported on Windows, Mac and Linux. > Postman is an API platform for building and using APIs. Postman simplifies each step of the API lifecycle and streamlines collaboration so you can create better APIs—faster. ## Functionalities 1. Syncing saved web requests (group as collections) 2. Teamwork 3. Mock server 1. Mock servers let you simulate endpoints and their corresponding responses in a collection without actually setting up a back end. 2. User define the default return value, postman will give you a mock server url. Developer could use the mock API to developer without a finished backend. 5. Monitor 1. A monitor lets you run a collection periodically to check for its performance and response 6. Build nice-looking documentation websites 7. Environments: define environment variables such as API key, protocol, port number, etc. 8. GraphQL Support 1. Import GraphQL schema file generated by codegen 2. Support auto-fetch if a GraphQL server is up (new changes to schema will be reflected in postman) 9. WebSocket + Socket.IO support 1. See [Postman Now Supports Socket.IO](https://blog.postman.com/postman-now-supports-socket-io/) 2. See [Using WebSocket Requests](https://learning.postman.com/docs/sending-requests/supported-api-frameworks/websocket/) 3. **Handshake path** can be set within **Settings**, do not include it in url 4. Socket.IO namespace can be set within URL right after hostname and port (i.e. `<hostname>:<port>/<namespace>`) 5. After connecting, you can subscribe to events with listeners 6. You can also send messages