How to add Postmancer to Claude Desktop

A standalone MCP server for API testing and management — let AI assistants call REST APIs in natural language. Paste the config into ~/Library/Application Support/Claude/claude_desktop_config.json and restart Claude Desktop.

Last updated June 14, 2026 · 28★ · stdio · no auth

Claude Desktop config for Postmancer

npm install -g postmancer

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

Setup steps

1Open Claude Desktop → Settings → Developer → Edit Config (this opens ~/Library/Application Support/Claude/claude_desktop_config.json).
2Paste the Postmancer config below under the top-level "mcpServers" key.
3Fill in any placeholder secrets (API keys, paths) in the snippet.
4Save the file, then fully quit and reopen Claude Desktop.
5Open a chat and confirm Postmancer's tools appear under the 🔌 tools menu.

Before you start

Node.js with npm/npx (to run the package), or Docker
A REST API to test against

What Postmancer can do in Claude Desktop

http_request

Send HTTP requests to any URL.

list_collections

View all your 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 from a collection.

set_environment_variable

Set variables for request templates.

get_environment_variables

View all environment variables.

Security

For production environments it is strongly recommended to set the encryption keys (POSTMANCER_ENCRYPTION_KEY for credentials/tokens, ENCRYPTION_KEY for secret environment variables) rather than using the defaults. If unset, a random key is generated for POSTMANCER_ENCRYPTION_KEY and a default key is used for ENCRYPTION_KEY.

Postmancer + Claude Desktop FAQ

Where is the Claude Desktop config file?

Claude Desktop reads MCP servers from ~/Library/Application Support/Claude/claude_desktop_config.json. Paste the Postmancer config there under the "mcpServers" key and restart the client.

Is Postmancer safe to use with Claude Desktop?

How do I run Postmancer?

Install it globally with `npm install -g postmancer` or run it directly via `npx postmancer`. A Docker image is also available.

Where are collections stored?

By default in `~/.postmancer`. You can change this with the `COLLECTIONS_PATH` environment variable.

How are credentials kept secure?

Credentials and tokens are encrypted using `POSTMANCER_ENCRYPTION_KEY`, and secret environment variables using `ENCRYPTION_KEY`. Setting these keys explicitly is strongly recommended in production.

View repo Full Postmancer page