postcatlab/postcat

★ 5,555JavaScriptAudience · developerComplexity · 2/5Setup · easy

Mindmap

mindmap
  root((postcat))
    What it does
      Send HTTP requests
      WebSocket testing
      Mock servers
      API documentation
    Platforms
      Windows
      Mac
      Linux
      Browser
    Tech
      Angular
      Electron
      Node.js 14 plus
    Status
      Maintenance mode
      Plugin system

mindmap root((postcat)) What it does Send HTTP requests WebSocket testing Mock servers API documentation Platforms Windows Mac Linux Browser Tech Angular Electron Node.js 14 plus Status Maintenance mode Plugin system

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Things people build with this

USE CASE 1

Test REST API endpoints by sending HTTP requests and inspecting responses without writing any code.

USE CASE 2

Run a mock server that returns fake API responses so your frontend can work before the real backend is ready.

USE CASE 3

Write and share API documentation alongside your requests in one tool.

USE CASE 4

Manage separate environment configs for development and production API endpoints and switch between them instantly.

Tech stack

JavaScriptTypeScriptAngularElectronNode.js

Getting it running

Difficulty · easy Time to first run · 30min

Project is in maintenance mode with no planned security fixes, evaluate risk before using in production workflows.

License terms were not described in the explanation.

In plain English

Postcat is an open-source API tool that runs on Windows, Mac, Linux, and in web browsers. API stands for application programming interface, which is the technical connection point between software systems. When a developer builds a backend service, they need a way to send test requests to it and see the responses. Postcat provides a graphical interface for doing exactly that, without writing custom code for every request. The tool supports HTTP REST and WebSocket protocols, which cover the most common types of APIs in use today. A plugin system lets users add extra capabilities to the base application without waiting for the core team to build every feature themselves. Support for additional protocols including GraphQL, gRPC, TCP, and UDP was planned on the roadmap. Beyond sending requests, Postcat includes tools for writing API documentation alongside your work, creating mock servers (fake versions of an API, useful for testing when the real backend is not yet ready), managing different environments such as development versus production settings, and sharing documents with teammates. The interface supports both English and Chinese. The project is now in maintenance mode. The original developers have stopped adding new features and will not be issuing security fixes going forward. Anyone using Postcat in a production environment is advised to evaluate the risks and consider migrating to an actively maintained alternative. For developers who want to run or modify the source code, the project requires Node.js 14.17 or newer and uses yarn as its package manager. It is built with Angular and Electron, which is how it runs both as a desktop application and in a browser from the same codebase.

Copy-paste prompts

Prompt 1

I have a REST API at /api/users returning JSON. Show me how to set up a Postcat request collection with a Bearer token auth header that I can reuse across requests.

Prompt 2

How do I create a mock server in Postcat that returns a 200 response with sample JSON data for /api/products?

Prompt 3

Set up Postcat with two environments pointing to localhost:3000 and my production API, show me how to switch between them without editing each request.

Prompt 4

How do I install Postcat plugins to add GraphQL support, and where do I find available plugins?

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