What Does a UUID Validator Do?
Paste any UUID to instantly check if it's valid. This free online UUID validator checks format, version, and variant in one click.
It validates:
- Format - correct 8-4-4-4-12 structure, 36 characters, hyphens in right positions
- Characters - only valid hexadecimal
0-9, a-f, A-F - Version - detects v1, v3, v4, v5, v6, v7, v8
- Variant - RFC 9562 compliant variant (8, 9, a, b)
- RFC Compliance - checks against RFC 9562 and legacy RFC 4122
Unlike a basic regex check, this tool tells you the UUID version, variant, and why it's invalid if it fails.
How to Validate a UUID Online
- Paste your UUID:
550e8400-e29b-41d4-a716-446655440000 - See instant result: valid or invalid, plus version, variant, and format breakdown
Works for UUID v4, UUID v7, UUID v1, v3, v5, v8 and GUIDs. Supports lowercase, uppercase, and bulk validation.
What Is UUID Version?
The version is encoded in the first digit of the third group. It's how software knows how the UUID was generated.
550e8400-e29b-41d4-a716-446655440000
^
version = 4
- UUID v4 - random. 122 random bits. Most common for user IDs, API keys.
- UUID v7 - time-ordered. 48-bit Unix timestamp + random. Sortable, better for database indexes. New in RFC 9562.
- UUID v1 - time + MAC address. Legacy, contains timestamp and node.
- UUID v5 - name-based with SHA-1. Deterministic from namespace + name.
Use v4 when you need random IDs. Use v7 when you need sortable, time-ordered IDs for databases.
What Is UUID Variant?
The variant tells you the UUID layout. For all modern UUIDs, it should be 8, 9, a, or b.
It's the first digit of the fourth group:
550e8400-e29b-41d4-a716-446655440000
^
variant = a (valid RFC 9562)
If variant is not 8, 9, a, b, the UUID is not RFC compliant.
Common Reasons a UUID Is Invalid
- Wrong length - not 36 characters (or 32 without hyphens)
- Missing or misplaced hyphens
- Invalid characters - contains g-z or symbols
- Wrong version - e.g., expecting v4 but got v1
- Wrong variant - fourth group doesn't start with 8, 9, a, b
- Extra spaces or braces -
{550e...}or copy-paste errors
Examples:
- Valid:
550e8400-e29b-41d4-a716-446655440000(v4) - Valid:
0191a2b3-c4d5-7e6f-8a9b-0c1d2e3f4a5b(v7) - Invalid:
550e8400-e29b-41d4-a716-44665544- too short - Invalid:
550e8400-e29b-41d4-g716-446655440000- contains g
UUID Validator Regex
If you need to validate in code, the basic format regex is:
^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$
For version-specific (v4 only):
^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
Use this tool to test your regex before deploying.
What This Validator Doesn't Check
A syntactically valid UUID may still not be usable in your app. This tool does not check:
- Whether the UUID exists in your database
- Whether it is unique in your system
- Who owns the resource
- Authorization or permissions
Validation is input checking. Existence and auth must be checked separately in application logic.
FAQ
Is this also a GUID validator? Yes. GUID and UUID use the same format. This validates both.
Does it support UUID v7? Yes, fully supports v7 including timestamp extraction.
Is it RFC 9562 compliant? Yes, validates against current RFC 9562 and legacy RFC 4122.
Can I validate multiple UUIDs at once? Yes, paste one per line for bulk validation.