Hello Keyboard ISBN Validator

Hello Keyboard ISBN Validator is a free online tool from Hello Keyboard Tools that checks whether an ISBN-10 or ISBN-13 is well-formed and has a valid check digit. Spaces and hyphens are removed automatically, and the result shows the ISBN format and a normalised number. A final X in an ISBN-10 is read as 10; any other non-digit character is rejected.

The calculation runs in the browser, no account is needed, and JavaScript must be enabled. It is handy for spotting typing mistakes when tidying reference lists, checking bibliographic records or entering book details.

Note that it only checks the format and check digit: it does not look up book information or confirm that an ISBN has actually been assigned to a book.