CUID Validator
Instantly verify if a string is a valid CUID format. Get detailed feedback about the validation result.
CUID Format Specification
A valid CUID must follow this exact format:
- Total length: Exactly 25 characters
- First character: Always lowercase 'c'
- Remaining characters: Lowercase letters (a-z) and numbers (0-9) only
- No special characters: No hyphens, underscores, or uppercase letters
Example Valid CUIDs
Example Invalid Strings
CL9EBQKXK0000MC04R8FZAGSYUppercase not allowedl9ebqkxk0000mc04r8fzagsyMust start with 'c'cl9ebqkxk0000mc04Too short (17 chars)Frequently Asked Questions
What does the CUID validator check?
The validator checks whether the string matches the CUID format, which is exactly 25 characters long and starts with "c". The remaining 24 characters are lowercase alphanumeric (a-z, 0-9).
Can the validator determine whether a CUID was generated using a CUID library?
No, the validator only checks the format. A string could match the CUID pattern even if it wasn't generated by an official CUID library. The validator confirms compliance with the format, not the origin.
Why is my CUID marked as invalid?
Common reasons for rejection include the following: incorrect length (must be exactly 25 chars), doesn't start with "c", contains uppercase letters, contains invalid characters (hyphens, underscores, etc.), or contains spaces.
Can I validate CUID2 with this tool?
This tool is designed specifically for CUID v1, which has a different format than CUID2 (no "c" prefix and variable length). Use our CUID2 Validator to check CUID2 strings.