test data · generator
Fake ISBN generator
Generate ISBN-10 and ISBN-13 numbers with valid check digits. Useful for book catalog testing, library system seeding, and bibliographic database staging.
beginner
seedable
Sample output
fakeit isbn --version=13 --count=3 --seed=42 9780306406157 9781861972712 9781234567897 fakeit isbn --version=10 --count=2 0306406152 1861972716
Safe vs unsafe examples
| Input | Result |
|---|---|
| 9780306406157 (ISBN-13 valid) | ✓safe to use |
| 0306406152 (ISBN-10 valid — 'The C Programming Language') | ✓safe to use |
| 9781861972712 (ISBN-13 valid) | ✓safe to use |
| **WARNING**: 9780306406158 (CHECK DIGIT WRONG — ends in 8, should be 7) | ✗avoid |
| 1234567890 (PUBLISHED ISBN-10 — may be a real book; test ISBNs should not collide with reality if possible) | ✗avoid |
Edge cases & caveats
ISBN-13 check: sum digits[i] × (1 if i even else 3), mod 10, subtract from 10. ISBN-10 check: sum digits[i] × (10-i) for i=0..8, mod 11, subtract from 11.
Note: see the warning above. Treat this page as a starting point, not a security control.
Common use cases
- Book catalog QA
- Library system staging data
- Bibliographic database seed
- Educational examples
Generate fake data at scale
fakeit generates realistic fake test data — names, emails, IBANs, ISBNs, phones, addresses. Seedable, schemable, MIT-licensed, no telemetry.
Open fakeit
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realistic names for testing · realistic names for testing · realistic names for testing · realistic names for testing