ISBN Validator
Free online ISBN validator. Verify ISBN-10 and ISBN-13 checksums, convert between formats, and catch data-entry errors. 100% client-side, private, bilingual EN/TH.
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What is ISBN Validator?
The ISBN Validator is a free online tool that checks whether an International Standard Book Number (ISBN) is structurally correct by verifying its check digit. It supports both the legacy 10-digit format and the current 13-digit format, and can convert a valid code between the two.
Key Benefits
- Catches typos and data-entry errors before they propagate into catalogs or orders
- Keeps databases consistent by converting between ISBN-10 and ISBN-13
- Works offline and client-side, protecting sensitive bibliographic data
- Accepts hyphenated and spaced input without manual cleanup
Common Use Cases
- •Librarians verifying ISBNs when cataloging new acquisitions
- •Booksellers and e-commerce teams validating product identifiers before listing
- •Publishers checking manuscript and cover ISBNs for consistency
- •Developers building book databases who need clean, normalized ISBNs
- •Students and researchers double-checking citations in bibliographies
How to Use the ISBN Validator
- Enter the ISBN: Type or paste the ISBN into the input field. Hyphens and spaces are allowed and will be normalized automatically.
- Choose a format (optional): Leave the format on Auto for automatic detection, or force ISBN-10 / ISBN-13 if you need a specific interpretation.
- Read the result: A green panel confirms a valid ISBN and shows the format; a red panel flags an invalid length or checksum mismatch.
- Convert or copy: For valid ISBNs, use the copy buttons to grab the normalized code or its converted ISBN-10 / ISBN-13 equivalent.
Key Features
- Validates both ISBN-10 (modulus 11) and ISBN-13 (modulus 10) checksums
- Automatic format detection with optional manual override
- Bi-directional conversion between ISBN-10 and ISBN-13 (978 prefix)
- Tolerates hyphens and spaces in input automatically
- Copy normalized or converted ISBNs to clipboard with one click
- 100% client-side processing for full privacy