Give Your AI Assistant API Testing Superpowers

Stop switching between Claude and Postman. Postmancer brings full REST client functionality directly into your AI assistant conversations, letting you test, debug, and document APIs without breaking your flow.

The Context Switching Problem

You're deep in a coding session with Claude, working through an API integration. The conversation is flowing, solutions are emerging, then you hit the inevitable: "Let me test this endpoint real quick."

Out comes Postman. You craft the request, test it, screenshot the response, paste it back into Claude. Flow broken. Context lost. This dance repeats dozens of times per project.

Your AI Assistant as a REST Client

Postmancer eliminates this friction by giving Claude (or any MCP-compatible AI) the ability to make HTTP requests, save collections, manage environments, and analyze responses - all within your conversation.

What you get:

• Native HTTP requests: Claude can test any endpoint directly with full header, auth, and body support
• Persistent collections: Save and organize requests that survive conversation restarts
• Environment management: Set variables once, use them across requests with automatic substitution
• Full auth support: Basic, Bearer, API key, and OAuth2 authentication methods
• Request history: Track what worked, what didn't, and iterate quickly

Where This Changes Everything

API Integration Debugging: Instead of describing error responses to Claude, it sees them firsthand. It can suggest fixes based on actual response codes, headers, and payloads.

Documentation Generation: Claude can test your entire API surface, then generate accurate docs based on real request/response patterns rather than guessing from code.

Environment Verification: Deploy to staging? Claude can validate your endpoints work as expected across different environments by running your saved collections.

Integration Testing: Build test suites conversationally. "Test the user creation flow" becomes a natural language command that executes a sequence of authenticated requests.

Quick Start

Install and configure in under two minutes:

npm install -g postmancer

Add to your Claude Desktop config:

{
  "mcpServers": {
    "postmancer": {
      "command": "npx",
      "args": ["-y", "postmancer"]
    }
  }
}

Now Claude can make requests like:

"Test the user registration endpoint with this payload and show me the response structure" - Claude executes the request, analyzes the response, and suggests improvements or next steps.

Security and Production Ready

Built with security in mind. Environment variables and credentials are encrypted locally. Your API keys never leave your machine, and you can use custom encryption keys in production environments.

The tool provides seven core capabilities through natural language:

• Send HTTP requests to any URL
• List and manage request collections
• Save requests for reuse
• Execute saved requests from collections
• Set environment variables with secret encryption
• View environment configurations
• Full request/response history tracking

This isn't about replacing your REST client - it's about making your AI assistant fluent in HTTP so you never have to leave the conversation to test an idea.

Your API development workflow just got conversational.