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Posted on • Originally published at 0nmcp.com

How to Connect Claude to Any API Using MCP (Step-by-Step)

#mcp #ai #claude #tutorial

Want Claude to send emails, create invoices, manage your CRM, or post to Slack? You need MCP — the Model Context Protocol.

This guide shows you how to connect Claude Desktop to any API in under 5 minutes using 0nMCP.

What is MCP?

MCP (Model Context Protocol) is the standard that lets AI assistants like Claude use external tools. Think of it as USB for AI — one protocol, unlimited devices.

Step 1: Install 0nMCP 

npm install -g 0nmcp
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Or use npx (no install needed):

npx 0nmcp
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Step 2: Add to Claude Desktop

Open your Claude Desktop config:

  • Mac: ~/Library/Application Support/Claude/claude_desktop_config.json
  • Windows: %APPDATA%\Claude\claude_desktop_config.json

Add this:

{
  "mcpServers": {
    "0nMCP": {
      "command": "npx",
      "args": ["-y", "0nmcp"]
    }
  }
}
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Restart Claude Desktop.

Step 3: Connect Your Services

Tell Claude: "Connect my Stripe account"

Or manually create connection files in ~/.0n/connections/:

{
  "$0n": { "type": "connection", "name": "stripe" },
  "service": "stripe",
  "auth": { "credentials": { "apiKey": "sk_live_..." } }
}
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Step 4: Use It

Now just talk to Claude naturally:

  • "Create a Stripe customer for sarah@example.com"
  • "Send a Slack message to #general: Deploy complete"
  • "List my last 10 GitHub issues"
  • "Add a row to my Google Sheet with today's metrics"

Claude uses 0nMCP to execute the API calls behind the scenes.

Supported Services (54 total)

Category Services
Communication Slack, Discord, Twilio, SendGrid, Gmail
Payments Stripe, Square, QuickBooks
CRM HubSpot, Pipedrive, custom CRM
Databases Supabase, MongoDB, Airtable, Notion
Developer GitHub, Linear, Jira, Vercel
AI OpenAI, Anthropic
Social LinkedIn, Twitter, Instagram
Google Sheets, Drive, Calendar, Ads

Also Works With

  • Cursor — Add to .cursor/mcp.json
  • Windsurf — Add to Windsurf MCP settings
  • Claude Code — Already works via stdio

Free and Open Source

Get started: npx 0nmcp

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