Developer utility APIs + remote MCP servers

Thirteen small, focused REST APIs for everyday developer jobs: validating emails, phones and IBANs, IP geolocation, PDFs, images, QR codes, fraud scoring, token counting and more. Each one is its own product on RapidAPI with a free plan, full OpenAPI docs, and a built-in remote MCP server so AI agents (Claude, Cursor, VS Code, n8n, LangChain) can call it as tools.

• Free tier on every API: subscribe on RapidAPI, copy your key, call it.
• MCP built in: every API exposes Streamable HTTP MCP at https://.p.rapidapi.com/mcp, and each is listed in the official MCP Registry as io.github.OlsOls4/.
• No heavy dependencies on your side: plain HTTPS + JSON from any language or no-code tool.

The APIs

Also available (newer):

• CurrencyKit: ECB euro reference exchange rates: latest, historical, time series and currency conversion. RapidAPI · MCP https://currencykit-ecb-exchange-rates-currency-converter.p.rapidapi.com/mcp
• VATKit: Live EU VAT number checks via VIES with company name/address, VAT formats and EU VAT rates. RapidAPI · MCP https://vatkit-eu-vat-number-check-vies-vat-rates.p.rapidapi.com/mcp

Quickstart (REST)

curl -G "https://calkit-public-holidays-business-days-timezones.p.rapidapi.com/business-days/add" \
  -d date=2026-12-23 -d days=5 -d country=GB -d subdiv=ENG \
  -H "X-RapidAPI-Key: YOUR_RAPIDAPI_KEY" \
  -H "X-RapidAPI-Host: calkit-public-holidays-business-days-timezones.p.rapidapi.com"

Swap the host for any API in the table. Every request goes through RapidAPI with X-RapidAPI-Key and X-RapidAPI-Host.

Quickstart (MCP)

Add any API as a remote MCP server in a client that supports Streamable HTTP with custom headers, for example:

{
  "mcpServers": {
    "calkit": {
      "type": "http",
      "url": "https://calkit-public-holidays-business-days-timezones.p.rapidapi.com/mcp",
      "headers": {
        "X-RapidAPI-Key": "YOUR_RAPIDAPI_KEY",
        "X-RapidAPI-Host": "calkit-public-holidays-business-days-timezones.p.rapidapi.com"
      }
    }
  }
}

The server answers tools/list with that API’s endpoints as tools.

What’s in this repo

• main.py and one folder per API (webkit, domainkit, qrkit, …): the FastAPI service behind all listings.
• mcpserver.py: the MCP layer that turns each API’s routes into tools.
• openapi/: OpenAPI specs for each API.
• mcp-registry/: server.json files published to the official MCP Registry.

Data and licences

GeoIP and FraudKit use DB-IP Lite (CC BY 4.0). UK PostcodeKit uses OS Code-Point Open (Open Government Licence v3.0; contains OS data © Crown copyright and database right). PhoneKit uses Google libphonenumber (Apache 2.0). Full attributions are in each API’s docs on RapidAPI.

Support

Questions, bugs or feature requests: open an issue or use the Discussions tab on the RapidAPI listing.