Postmancer is a standalone MCP (Model Context Protocol) server for API testing and management, allowing AI assistants to interact with RESTful APIs through natural language. It is designed as an experimental alternative to tools such as Postman and Insomnia, but specifically for AI assistants.
Main capabilities
Postmancer provides the following tools for AI assistants:
- http_request: Send an HTTP request to any URL
- list_collections: View all saved API collections
- list_requests: View all requests in a collection
- save_request: Save a request to a collection
- request_from_collection: Execute a saved request
- set_environment_variable: Set a variable for request templates
- get_environment_variables: View all environment variables
In addition, it supports saving and organizing requests into collections, setting and using environment variables and variable substitution, multiple authentication methods (Basic, Bearer, API Key, OAuth2), as well as request/response history and testing.
Usage
Using it in Claude Desktop: Add the configuration to the Claude Desktop configuration file.
- Windows: %USERPROFILE%.claude\claude_desktop_config.json
- macOS/Linux: ~/.claude/claude_desktop_config.json
It is also supported for use via Docker.
Postmancer can be configured through the following environment variables:
- COLLECTIONS_PATH: The path where collections are stored (default: ~/.postmancer)
- LOG_LEVEL: Log level (debug, info, warn, error) (default: info)
- POSTMANCER_ENCRYPTION_KEY: The key used to encrypt credentials and tokens (a random key is generated when not provided)
- ENCRYPTION_KEY: The key used to encrypt environment variables marked as secret (a default key is used when not provided)
Use cases
Suitable for scenarios where you need to send HTTP requests through an AI assistant in natural language, manage collections of API endpoints, test API responses, and save and organize requests, and can replace some functions of Postman or Insomnia.
Limitations
The project is labeled as "experimental." For production environment security, it is strongly recommended to set the above encryption keys rather than using the default values.
