Check Digit Validator: Card Luhn, ISBN, EAN, ISIN, CUSIP, SEDOL

Use when: an AI agent or app needs to check that a card number, ISBN, EAN/UPC, ISIN, CUSIP, SEDOL, US ABA routing number or IMEI is well-formed (correct check digit), detect its type and convert between ISBN-10/13 or CUSIP/SEDOL to ISIN, before using it.

Try this input (also the default, just click Start)

{"requests": ["4111 1111 1111 1111", "978-0-306-40615-7", "US0378331005", "0263494", {"value": "4111111111111112", "type": "card"}]}

Sample output (real run, 2 Nov 2026, trimmed)

{"value": "4111 1111 1111 1111", "type": "card", "brand": "Visa", "masked": "411111******1111", "test_number": true, "valid": true, "result": "valid", "error": null}
{"value": "978-0-306-40615-7", "type": "isbn13", "isbn10_equivalent": "0306406152", "valid": true, "error": null}
{"value": "0263494", "type": "sedol", "isin_gb": "GB0002634946", "valid": true, "error": null}
{"value": "4111111111111112", "type": "card", "valid": false, "expected_check_digit": "1", "result": "invalid check digit", "error": null}

Options

• Each item: a string, or {"value": "...", "type": "card|isbn10|isbn13|gtin|isin|cusip|sedol|aba|imei"}. Type is auto-detected if omitted.

Each row has type, normalized, valid, expected_check_digit, result and conversions where they apply. Card numbers are masked in output. Up to 100000 items per run; no network calls, nothing stored.

Pricing: pay per event, $0.001 per checksum validation (one identifier validated). Rows with errors are not charged. No subscription.

Limits & failure modes

• Checksum only: a valid result means well-formed, not that the card, book or security exists or is active.
• Card brand is from the number prefix; no BIN/IIN bank database.
• Auto-detect can be ambiguous for short numeric strings (e.g. 9-digit CUSIP vs ABA); pass type to be sure.
• Published check-digit algorithms only.

Last tested: 2 Nov 2026.

Use from AI agents (MCP)

• Apify MCP server: add https://mcp.apify.com/?tools=tudorlane/card-and-id-checksums to Claude, Cursor, ChatGPT, VS Code or any MCP client.
• REST: POST https://api.apify.com/v2/acts/tudorlane~card-and-id-checksums/run-sync-get-dataset-items?token=YOUR_TOKEN with the input JSON.