UUID Validator

Validate the structure and version of any UUID string.

This tool runs entirely in your browser. Nothing you type is uploaded, logged or stored, which makes it safe for keys, tokens and other sensitive values.

What Is UUID Validator?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. It is written as 32 hexadecimal digits in five groups separated by hyphens, following the 8-4-4-4-12 structure, for a total of 36 characters including the hyphens.

This validator checks whether a string matches the UUID format defined by RFC 4122. It verifies the overall structure, the hexadecimal characters, the version nibble (which indicates the UUID version), and the variant bits (which indicate the layout of the identifier).

Format validation is different from semantic validation. A UUID can be structurally valid without being a real identifier that exists in any system. This tool confirms that the string is a well-formed UUID and reports which version it claims to be.

How to Use UUID Validator

  1. Paste or type a UUID into the input field.
  2. The validator checks the format instantly as you type.
  3. A valid UUID shows a green confirmation; an invalid one shows a red error.
  4. Use the example UUID to see a valid format.

Features

  • Instant format validation as you type.
  • Checks the 8-4-4-4-12 structure and hexadecimal characters.
  • Verifies the version nibble and variant bits per RFC 4122.
  • Clear valid/invalid visual feedback.
  • Fully client-side — no UUID is transmitted.

Common Use Cases

  • Confirming that an identifier from a database export or API response is well-formed.
  • Catching copy-paste errors in UUIDs before using them in queries or requests.
  • Validating user-supplied identifiers in forms and APIs.
  • Learning the UUID structure by testing valid and invalid examples.

How It Works

A UUID is 32 hexadecimal digits (0-9, a-f) arranged as 8-4-4-4-12 with hyphens. The 13th digit (the first digit of the third group) is the version, which is 1, 2, 3, 4, or 5 for the standard versions. The 17th digit (the first digit of the fourth group) encodes the variant and must be 8, 9, a, or b for an RFC 4122 UUID.

This tool checks all of those constraints with a single regular expression and reports whether the input is a valid RFC 4122 UUID. It does not look up whether the UUID refers to a real record.

Validation runs entirely in your browser. No UUID is sent anywhere.

Security and Privacy Considerations

Validation confirms format only. A valid UUID is not necessarily authorized, real, or safe to use. Always enforce authorization on the server when acting on an identifier.

Do not rely on UUID format validation as a security control. It catches malformed input, not malicious intent.

All validation is local, so no identifier leaves your device.

When to Use UUID Validator

  • Confirming that an identifier from a database export or API response is well-formed.
  • Catching copy-paste errors in UUIDs before using them in queries or requests.
  • Validating user-supplied identifiers in forms and APIs.
  • Learning the UUID structure by testing valid and invalid examples.

When Not to Use UUID Validator

  • As a security control — validation confirms format only, not authorization or existence.
  • To confirm a UUID refers to a real record — format validation cannot do that.
  • As a substitute for server-side authorization when acting on an identifier.

Comparison

  • UUID validator vs UUID generator: the validator checks an existing string against the RFC 4122 format; the generator creates new random v4 identifiers. Use the validator to check input and the generator to produce new IDs.
  • Validation vs lookup: this tool checks structure only. Confirming that a UUID exists in your system requires a database or API lookup, which is outside the scope of format validation.

Frequently Asked Questions

What is the UUID format?
A UUID is 32 hexadecimal digits in five groups separated by hyphens, following the 8-4-4-4-12 structure, for 36 characters total including hyphens.
What UUID versions are recognized?
The standard versions are v1 (time-based), v2 (DCE Security), v3 (name-based with MD5), v4 (random), and v5 (name-based with SHA-1). This validator checks the version nibble to confirm the claimed version.
Does a valid UUID mean the identifier exists?
No. Format validation confirms the string is well-formed; it does not confirm the UUID refers to a real record in any system.
What makes a UUID invalid?
Common issues include missing or extra hyphens, non-hexadecimal characters, wrong group lengths, an invalid version nibble, or an invalid variant.
Is my UUID uploaded?
No. Validation happens entirely in your browser.

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