ISBN-13 check digit

Client

Book identifier checksum helper.

ISBN-13 check digit

Computes or verifies the mod-11 ISBN-13 check digit from 12 body digits—no publisher directory lookup. Processing runs in your browser—Toolcore does not need your paste for the core operation on this page.

Format and checksum rules only—no live registry lookup.

How to use

Paste or type in the main field, then read the output below. Use Load example when available, or open the page with ?q= / ?qb= so tickets and agents share the same input.

Loading…

Nearby workflows on Toolcore

  • GTIN checksum (EAN / UPC) — Paste GTIN‑8, UPC‑A (GTIN‑12), EAN‑13, or logistic GTIN‑14 digits—ISO GS1 modulus‑10 parity without GS1 lookup—browser-only. Useful when another column uses a different identifier ruleset.
  • Luhn checksum (mod 10) — Paste a digit string (spaces ignored)—pass or fail Luhn for PANs, IMEI-style IDs, and test vectors; browser-only. Useful when another column uses a different identifier ruleset.
  • E.164 phone normalize — Strip formatting, normalize + / 00 / 011, validate ITU-style length; NANP +1 hint for 10-digit US/CA style—local only. Useful when another column uses a different identifier ruleset.
  • Identity tools — UUID v4 and time-ordered UUID v7, MongoDB ObjectId parse/generate, sortable ULID, Nano ID, and E. Useful when another column uses a different identifier ruleset.

Common use cases

  • ISBN-13 check digit for quick local checks without uploading data.
  • Copy results into tickets, docs, or classroom notes.

Common mistakes to avoid

  • Unexpected input shape

    See the intro and how-to notes for accepted formats.

FAQ

Is processing local?

Yes—this runs entirely in your browser.

Agent prefill?

Use q or qb for the main text field when supported.

More tools

Related utilities you can open in another tab—mostly client-side.