Dev
Fake ISBN Generator
Building a bookstore, library catalog, or reading-list app means seeding your database with book records — and every book record needs an ISBN. Using real ISBNs ties your test data to actual books, while purely random strings fail format validation. This tool generates ISBN-13 numbers that are structurally correct, including the check digit, so they pass validation without referencing any real publication. The only input is how many you want, from 1 to 20. The generator randomly uses either the 978 or 979 prefix, fills nine random middle digits, and computes the correct modulo-10 check digit. The result is formatted with standard hyphenation: prefix, publisher group, title segment, and check digit. Copy a batch into seed scripts or fixture files for your ORM. They will pass any ISBN-13 validator, which means your validation logic gets exercised realistically without needing to borrow ISBNs from a real catalog API.
How to use
- Choose your options above
- Click Generate
- Copy your result
Detailed instructions
- Choose how many fake ISBNs you want.
- Click Generate to produce valid-format ISBN-13s.
- Copy them into your seed data or fixtures.
- Use them only for testing, not as real data.
Use Cases
- •Seed data for a bookstore or library app
- •Test fixtures that need valid-format ISBNs
- •Placeholder ISBNs in UI mockups
- •Validating ISBN format and checksum logic
- •Populating a catalog database for demos
Tips
- →Use these for test data, never as real ISBNs.
- →They pass checksum validation by design.
- →Generate a batch for bulk seed data.
- →Pair with a fake book-title generator for full records.
FAQ
are these real ISBNs
No — they are format-valid but fictional. Each has a correct ISBN-13 structure and check digit, so it passes validation, but it does not correspond to a real published book. Use them only for testing, never as genuine catalog data.
how is the check digit calculated
The ISBN-13 check digit uses a modulo-10 algorithm that alternately weights each of the first 12 digits by 1 and 3, sums the products, and derives the check digit from the remainder. This generator applies that same calculation, so the resulting numbers pass standard checksum validators.
do these pass ISBN validation
Yes — each number includes a correctly computed ISBN-13 check digit, so it passes standard format and checksum validation. That makes them ideal for testing code paths that validate ISBNs before storing or displaying them.
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