UUID Validator

Check if your string is a valid UUID (v1, v3, v4, or v5). Paste a UUID below to validate its format.

UUID Validation

Check if a string is a valid UUID format. This tool verifies the structure (8-4-4-4-12 hex digits with hyphens), identifies the UUID version, and checks the variant bits.

Useful for validating user input, debugging data issues, or checking imported data that should contain UUIDs.

Valid Format

xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
M = version (1-5)
N = variant (8, 9, a, or b)

Understanding UUIDs

UUIDs (Universally Unique Identifiers) are 128-bit numbers used to identify information in computer systems without requiring a central authority. The standard representation is a 36-character string in the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, using hexadecimal digits. UUIDs are fundamental to distributed systems where unique identification without coordination is essential.

The probability of generating duplicate UUIDs is astronomically low'so low that it's considered practically impossible under normal circumstances. This makes them ideal for database primary keys, session identifiers, transaction IDs, and any scenario requiring globally unique identifiers without centralized ID generation.

UUID Versions Explained

  • Version 1:Generated from timestamp and MAC address; reveals creation time and machine
  • Version 3:Created by hashing a namespace and name using MD5
  • Version 4:Generated from random numbers; most commonly used today
  • Version 5:Similar to v3 but uses SHA-1 hashing instead of MD5

When to Use UUIDs

UUIDs excel in distributed databases, microservices architectures, and systems where records may be created offline and synchronized later. They're also useful when you want to hide sequential ordering (unlike auto-increment IDs that reveal how many records exist) or when merging data from multiple sources.

Our validator checks UUID format compliance including proper length, character set (hexadecimal only), hyphen placement, and version nibble. Valid UUIDs should be 36 characters with hyphens at positions 8, 13, 18, and 23. Always validate UUIDs received from external sources before processing to prevent errors and potential security issues.

Frequently Asked Questions

Why is my UUID showing as invalid?

Common issues include wrong length (must be 36 characters with hyphens), non-hexadecimal characters, hyphens in wrong positions, or missing the version digit. Double-check the format: 8-4-4-4-12 hexadecimal characters.

Should I store UUIDs with or without hyphens?

Both are valid. With hyphens is more readable; without hyphens saves 4 characters. Databases like PostgreSQL have native UUID types that store them efficiently regardless of format. Be consistent within your application.

Are uppercase and lowercase UUIDs the same?

Yes. UUIDs are case-insensitive"ABC" and "abc" represent the same hex values. Our validator accepts both. For consistency, most systems store UUIDs in lowercase, but uppercase is equally valid.

What is a NIL UUID?

The NIL UUID is all zeros (00000000-0000-0000-0000-000000000000). It's used as a placeholder or null value in systems that require UUID format but need to represent "no value" or "unknown." Our validator recognizes it as a valid UUID format.