OIB Validator (Croatia Tax ID / Personal ID)
Validate authenticity, structure, and ISO 7064 checksum of Croatian OIB numbers.
About Croatian OIB Validation
This tool inspects the 11 digits of the OIB, ensuring proper length and verifying that the 11th digit matches the official ISO 7064 Module 11, 10 algorithm.
Fast, real-time client-side validation executed in memory with complete privacy.
OIB Validation Algorithm
- Remove whitespace and dashes, verifying the string contains exactly 11 numeric digits.
- Run the ISO 7064 Mod 11, 10 accumulator loop across the first 10 digits.
- Compute expected control digit (11 - a).
- Compare with the 11th digit of the input document.