CalKit

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://<host>.p.rapidapi.com/mcp, and each is listed in the official MCP Registry as io.github.OlsOls4/<kit>.
• No heavy dependencies on your side: plain HTTPS + JSON from any language or no-code tool.

The APIs

API	What it does	RapidAPI	MCP endpoint	Tutorial
WebKit	Email validation, link previews and article-to-Markdown extraction for AI agents	Listing	https://webkit-email-validator-link-preview-article-extractor.p.rapidapi.com/mcp	dev.to
DomainKit	DNS records, SSL certificate, WHOIS/RDAP and website tech scan for any domain	Listing	https://domainkit-dns-ssl-whois-website-tech-lookup.p.rapidapi.com/mcp	dev.to
QRKit	Generate QR codes (URL, WiFi, vCard) and barcodes as PNG/SVG	Listing	https://qrkit-qr-code-barcode-generator.p.rapidapi.com/mcp	dev.to
TextKit	Sentiment, language detection, readability, keywords, summaries and profanity filtering	Listing	https://textkit-sentiment-language-readability-keywords.p.rapidapi.com/mcp	dev.to
PhoneKit	Phone number validation, formatting, carrier, line type and timezone	Listing	https://phonekit-phone-number-validation-carrier-line-type.p.rapidapi.com/mcp	dev.to
ValidKit	Validate IBAN, EU VAT, card numbers, ISBN, BIC, EAN and postcodes	Listing	https://validkit-iban-vat-card-isbn-bic-postcode-validator.p.rapidapi.com/mcp	dev.to
GeoIP	IP geolocation: country, continent, ASN and ISP lookup	Listing	https://geoip-ip-geolocation-asn-isp-lookup.p.rapidapi.com/mcp	dev.to
DocKit	Extract text and metadata from PDFs; convert Markdown or text to PDF	Listing	https://dockit-pdf-text-extraction-markdown-to-pdf.p.rapidapi.com/mcp	dev.to
FraudKit	Fraud risk score for signups and orders from email, IP, phone and user-agent	Listing	https://fraudkit-fraud-risk-score-for-signups-orders.p.rapidapi.com/mcp	dev.to
ImageKit	Resize, convert to WebP, compress, crop, rotate and strip EXIF from images	Listing	https://imagekit-resize-convert-to-webp-compress-crop.p.rapidapi.com/mcp	dev.to
UK PostcodeKit	UK postcode lookup, nearest postcodes, autocomplete and distance (OS open data)	Listing	https://uk-postcodekit-postcode-lookup-nearest-distance.p.rapidapi.com/mcp	dev.to
LLMKit	Token counting, RAG chunking, truncation, HTML to Markdown and JSON repair	Listing	https://llmkit-token-counter-rag-chunker-json-repair.p.rapidapi.com/mcp	dev.to
CalKit	Public holidays for 150+ countries, business-day maths and timezone lookup	Listing	https://calkit-public-holidays-business-days-timezones.p.rapidapi.com/mcp	dev.to

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.