Checksum Validator

Validate or compute check digits for IBAN, ISBN-10, and ISBN-13 identifiers.

Free tier eligible — 500 calls/month with a free key from /pricing; x402 pay-per-call above quota.

Parameters

Parameter	Type	Required	Description
`scheme`	string	optional	Checksum scheme One of: iban, isbn10, isbn13
`value`	string	required	Value to check (spaces/dashes ignored)
`mode`	string	optional	validate or check_digit One of: validate, check_digit

Call it over MCP (JSON-RPC 2.0)

curl -s https://wingmanprotocol.com/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": {"name": "checksum", "arguments": {"value": "example"}}}'

Or plain HTTP

curl -s https://wingmanprotocol.com/tools/checksum \
  -H 'Content-Type: application/json' \
  -d '{"value": "example"}'

Try it live

Edit the JSON and run it — this POSTs to https://wingmanprotocol.com/tools/checksum from your browser.

This tool is x402-metered — agents pay per call with USDC on Base. The 402 response below is the standard x402 payment-requirements envelope: sign the EIP-3009 authorization and retry with the X-Payment header, or get a free key at /pricing (500 calls/month, no card, no crypto).