One URL for every assistant

Run all 34 C99 APIs and check your plan, expiration date, limits and usage from Claude, ChatGPT, Cursor, VS Code or any MCP client.

You need a C99 account

When connecting, you sign in with your C99 dashboard account and approve access. No API key copying needed.

Get an API key Log in
Claude

claude.ai & Claude Desktop

Add C99 as a custom connector. You'll be asked to sign in to C99 and approve access, no API key needed.

  1. Open Settings → Connectors in Claude.
  2. Click Add custom connector, name it C99.nl and paste https://beta.c99.nl/mcp as the URL.
  3. Click Connect, sign in with your C99 account and press Allow.
Open Claude connectors Custom connectors may depend on your Claude plan or your organization's settings.
Claude Code

Claude Code (terminal)

Run this once, then type /mcp inside Claude Code to sign in.

claude mcp add --transport http c99 https://beta.c99.nl/mcp
Prefer an API key over signing in? Use: 
claude mcp add --transport http c99 https://beta.c99.nl/mcp --header "X-Api-Key: YOUR_API_KEY"
ChatGPT

ChatGPT

ChatGPT supports custom MCP connectors in developer mode.

  1. In ChatGPT, open Settings → Apps & Connectors → Advanced settings and turn on Developer mode.
  2. Create a new connector with the URL https://beta.c99.nl/mcp and OAuth authentication.
  3. Sign in with your C99 account and press Allow.
Menu names can differ per ChatGPT plan and version.
Editors

Cursor & VS Code

One click installs the server; the editor then opens the C99 sign-in page.

Cursor Or add it to ~/.cursor/mcp.json
Add to Cursor 
{
    "mcpServers": {
        "c99": {
            "url": "https://beta.c99.nl/mcp"
        }
    }
}
VS Code Or add it to .vscode/mcp.json
Add to VS Code 
{
    "servers": {
        "c99": {
            "type": "http",
            "url": "https://beta.c99.nl/mcp"
        }
    }
}
Other clients

Any MCP client with an API key

Clients without OAuth support can send your key in the X-Api-Key header (or as Authorization: Bearer). Transport: Streamable HTTP.

{
    "mcpServers": {
        "c99": {
            "type": "http",
            "url": "https://beta.c99.nl/mcp",
            "headers": {
                "X-Api-Key": "YOUR_API_KEY"
            }
        }
    }
}
What you get

Available tools

Try asking: "When does my C99 plan expire?", "How many requests do I have left this month?" or "Find the subdomains of example.com".

Your account Free, no requests used
  • Account overview
  • Hourly API limits
  • Usage statistics
  • Recent requests
APIs Count toward your normal limits
  • Subdomain Finder
  • IP Reputation/Malicious IP Checker
  • Phone Number Lookup
  • Firewall Detector
  • Get Hostname
  • DNS Checker
  • Gets the IP behind a host
  • IP to Domains
  • WHOIS Lookup
  • GeoIP Lookup
  • Up or Down Checker
  • URL Reputation Checker
  • Get HTTP Headers
  • Link Backup (Archive.org)
  • Dictionary Lookup
  • Email Validator
  • Disposable Email Checker
  • IP Address Validator
  • Tor Exit Node Checker
  • Translate Text
  • Random Person Generator
  • YouTube Video Details
  • View IP Loggers
  • View IP Logger Logs
  • Bitcoin Address Balance
  • Currency Converter
  • Currency Rates
  • Currency Rates
  • Weather Information
  • QR Code Generator
  • Password Generator
  • Random Number Generator
  • License Key Generator
  • Search GIFs
Good to know

Limits & security

  • API calls made by your assistant use your normal hourly and monthly limits. Checking your account does not.
  • Your IP whitelist, user-agent lock and other key restrictions still apply. Hosted assistants like claude.ai and ChatGPT call from their own servers, so a strict IP whitelist or user-agent lock will block them.
  • See and disconnect approved apps anytime under Account → Connected Apps/MCP. Setups that use your API key stop working when you reset the key in Settings.