UUID Validator
Validate and inspect UUID/GUID formats and versions
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
About this tool
Check whether a string is a correctly formatted UUID/GUID, and if valid, identifies which version it is (v1, v4, etc.) based on its structure. Useful for debugging data validation issues, or understanding what type of UUID a system generated.
How to use this tool
- Paste UUID valueInput any ID string you want to validate against UUID rules.
- Run format validationCheck length, character set, hyphen placement, and variant bits.
- Inspect detected versionIdentify generation type (v1, v4, etc.) from encoded bits.
- Fix source system if invalidUpdate generators, schemas, or validators causing malformed IDs.
Reading a UUID’s version
The version is the first digit of the third group: in 123e4567-e89b-42d3-a456-426614174000 it is 4, a random UUID. Version 1 is based on time and a machine address, version 4 is random, and version 7 starts with a timestamp, so IDs created later sort later.
That ordering is why many databases now prefer UUID v7 for primary keys: new rows are added in order, which keeps indexes compact.
Key features
- Quickly identifies malformed IDs before they break workflows.
- Clarifies UUID version differences for engineering teams.
- Useful in API validation and data ingestion debugging.
- Reduces time spent tracing identifier-format errors.
Common uses
- Debugging API requests failing UUID schema checks.
- Validating imported database IDs during migration.
- Verifying generated IDs in distributed systems.
- Checking third-party payload conformance quickly.
Tips for better results
- Normalize casing and hyphen style in one canonical format.
- Validate at input boundary before storage/use.
- Use version-specific rules if business logic depends on generation type.
- Log invalid UUID samples for upstream system fixes.
Mistakes to avoid
- Assuming any 36-char string is valid UUID.
- Ignoring variant/version bits in strict integrations.
- Mixing UUID and non-UUID identifiers in same field silently.
- Skipping validation on external API payloads.
Frequently asked questions
It indicates how the UUID was generated - version 1 is based on timestamp and network info, version 4 is purely random, and other versions use different generation methods. The version is encoded directly in specific bits of the UUID itself.
Yes - the version just describes the generation METHOD, not a unique identifier itself; many different UUIDs can share the same version number while still being completely distinct values.
Wrong length, invalid characters, incorrect hyphen placement, or a version/variant bit pattern that doesn't match any recognized UUID standard - the validator checks the string against the formal UUID structure.
Version 7 UUIDs start with a timestamp, so new IDs sort in creation order. That keeps database indexes compact and inserts fast, unlike random v4 UUIDs scattered across the index.
Yes. GUID is Microsoft's name for the same 128-bit identifier; .NET and Windows tools print them in the same 8-4-4-4-12 format, sometimes in braces.
In theory, but for random v4 UUIDs the odds are negligible: you would need to generate billions per second for many years before a duplicate became likely.