Valid UUID v4
- Input
- 550e8400-e29b-41d4-a716-446655440000
- Expected output
- Válido — v4, variante RFC 4122
Hex 4 at position 13 indicates version 4 (random).
validate uuid online
Validate UUID online
Validating UUIDs is essential in APIs and distributed systems: a malformed UUID in a REST route can cause hard-to-debug errors. This page explains how to recognise a valid UUID by the standard and how to interpret its structural fields.
Anatomy of a UUID
- A canonical UUID has the format xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx, where M is the version nibble (1–8) and N is the variant nibble (8, 9, a or b for RFC 4122).
Validation examples
Invalid string
- Input
- 12345678-1234-1234-1234-12345678901g
- Expected output
- Inválido — caractere não-hexadecimal
'g' is not a valid hexadecimal digit.
Full tool FAQ
A UUID v4 is a 128-bit unique identifier generated with random bits, except for the 4 version bits (position 13) and 2 variant bits (position 19). The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where y is 8, 9, a or b.
Frequently asked questions
What is the difference between UUID v1 and v4?
UUID v1 is based on timestamp + MAC address, ensuring temporal ordering but exposing hardware information. UUID v4 is fully random, more private but without intrinsic ordering. For databases with many inserts, UUID v7 (timestamp-based, RFC 9562) offers the best of both worlds.
Does this page replace official or professional review?
No. It helps explain the scenario and use the tool more safely, but real decisions should consider official sources, full context and qualified guidance when needed.