MCP server · Security
Captcha MCP server
Lets your AI solve a small proof-of-work puzzle or pay a tiny Lightning fee to earn access to a rate-limited service.
This is a small helper that sits in front of an MCP server and makes callers earn their next request. Instead of being told "slow down" with a plain error, your AI gets a small puzzle to solve (free, a few seconds of thinking) or a tiny Lightning payment to make. It is handy for anyone running or using an MCP server that gets hammered by too many automated calls.
What is an MCP server? The 30-second version
On its own, your AI can only chat. An MCP server is a small helper program that gives your AI a new skill or a connection to a service. This one connects your AI to the PowForge captcha service, which hands out proof-of-work puzzles and Lightning payment challenges. With it connected, your AI can ask for a puzzle, solve it, and get a short-lived pass to call a protected service.
What this MCP server does
You (or your AI) ask for a fresh puzzle. The helper talks to the PowForge captcha service and gets back a small challenge with a difficulty level. Your AI then does some quick number crunching to find a solution, which usually takes a few seconds. It sends that solution back, and the helper returns a signed pass that works for about five minutes. If your AI would rather pay than compute, it can take the Lightning route instead.
Click to zoomWhat you can do with it
- Request a fresh proof-of-work puzzle from the captcha service
- Submit a solved puzzle and receive a short-lived access pass
- Check the service health, lifetime stats, and payment endpoint details
- Use the free puzzle tier instead of paying anything
- Use the paid Lightning tier (about 3 sats) to skip the puzzle
- Run it locally over stdio or as a small web endpoint
Try asking your AI
- “Get me a new captcha challenge so I can call the protected service”
- “Solve this proof-of-work puzzle and give me the access token”
- “Check the captcha service status and tell me what the payment endpoint looks like”
- “I would rather pay than solve. Show me the Lightning invoice details”
What it gives back to you
You get back small structured answers in the chat. A challenge comes as an id, a salt, a difficulty number, and a signature. A solved challenge comes back as a signed token that lasts about five minutes. A status check returns health information, lifetime counts, and details about the paid option.
Before you start
What you need
- Node.js installed on your computer (the helper runs with npx)
- An MCP-compatible app like Claude Desktop, Claude Code, or Cursor
- Internet access to reach the captcha service (or a local copy of it running)
Good to know
The paid tier spends real money over Lightning (about 3 sats per call), and the free tier uses a few seconds of your computer's processing time for each puzzle.
Install it with your AI
Add Captcha MCP server to your AI, no technical skills needed
You don't install anything by hand. You copy one prompt, paste it into an AI that can work on your computer, and it checks, installs and connects the server for you, asking you when it needs something.
Sign in to get the install prompt
Members get a ready-made prompt that lets the Claude desktop app check Captcha MCP server, install it and connect it for them, step by step. You don't need any technical skills: you copy, paste and answer a few questions. Your connected AI can also find and install any of the 4,066 MCP servers here for you.
Who it's for
People who run or use MCP servers that get flooded by automated callers, and anyone curious about giving their AI a small cost-based gate before it makes a request.
