What is Postmancer

Postmancer is an experimental MCP server Rest Client designed to replace tools like Postman and Insomnia, enabling AI assistants to interact with RESTful APIs using natural language.

Use cases

Use cases for Postmancer include automating API testing, managing API requests in collections for easy access, and enabling AI assistants to perform complex API interactions through natural language commands.

How to use

To use Postmancer, install it globally via npm or run it directly with npx. For integration with Claude Desktop, add the configuration to the appropriate config file. It can also be run using Docker for containerized environments.

Key features

Key features of Postmancer include making HTTP requests to any REST API, organizing requests in collections, supporting multiple authentication methods, managing environment variables, and providing request/response history for testing.

Where to use

Postmancer can be used in various fields such as software development, API testing, and automation where AI assistants are employed to streamline API interactions.

Postmancer

A standalone MCP server for API testing and management, allowing AI assistants to interact with RESTful APIs through natural language.

Overview

Postmancer is an MCP (Model Context Protocol) server that enables AI assistants like Claude to make HTTP requests, manage collections of API endpoints, and test API responses. It provides similar functionality to tools like Postman or Insomnia but designed specifically for AI assistants.

Features

• Make HTTP requests to any REST API
• Save and organize requests in collections
• Set and use environment variables with variable substitution
• Multiple authentication methods (Basic, Bearer, API Key, OAuth2)
• Request/response history and testing

Quick Start

Installation

# Install globally
npm install -g postmancer

# Or run directly with npx
npx postmancer

Using with Claude Desktop

Add this to your Claude Desktop configuration file:

• Windows: %USERPROFILE%\.claude\claude_desktop_config.json
• macOS/Linux: ~/.claude/claude_desktop_config.json

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

Using with Docker

docker run -i --rm \
  --mount type=bind,src=/path/to/collections,dst=/data/collections \
  postmancer

Available Tools

Postmancer provides the following tools to AI assistants:

1. http_request - Send HTTP requests to any URL
2. list_collections - View all your saved API collections
3. list_requests - View all requests in a collection
4. save_request - Save a request to a collection
5. request_from_collection - Execute a saved request
6. set_environment_variable - Set variables for request templates
7. get_environment_variables - View all environment variables

Configuration

Configure Postmancer with these environment variables:

• COLLECTIONS_PATH: Path to store collections (default: ~/.postmancer)
• LOG_LEVEL: Logging level (debug, info, warn, error) (default: info)
• POSTMANCER_ENCRYPTION_KEY: Secret key used to encrypt credentials and tokens (generates a random key if not provided)
• ENCRYPTION_KEY: Secret key used to encrypt environment variables marked as secrets (uses default key if not provided)

For security in production environments, it’s strongly recommended to set these encryption keys rather than using the defaults.

License

MIT