How do I validate a UUID or decode a v7 timestamp?

Paste the value in the inspector. It accepts 32 hexadecimal characters or complete 8-4-4-4-12 groups, optionally enclosed in balanced braces, and accepts upper or lower case. A readable representation is reported separately from a recognized version and variant. Nil and Max have special labels. Only an RFC-variant v7 gets an embedded timestamp display; the timestamp does not prove when or by whom the value was made. V4 has no timestamp to extract.

How many characters and bytes are in a UUID?

A UUID is 128 bits, or 16 bytes. Its canonical hexadecimal text has 36 characters: 32 hexadecimal digits and four dashes. No dashes gives 32 characters; braces add two more. A 16-character or 16-bit value is not a complete UUID. The output download is a UTF-8 text list, not a binary 16-byte UUID file or a shortened-ID encoding.

What are Nil, Max and the UUID variant?

Nil is 00000000-0000-0000-0000-000000000000 and Max is ffffffff-ffff-ffff-ffff-ffffffffffff. They are special all-zero and all-one values. The variant bits identify a UUID layout: this tool generates the RFC variant and names legacy NCS, Microsoft and reserved variants when inspecting a value. A readable string with an unrecognized version or legacy variant is not labelled as a recognized modern layout.

Does a readable UUID prove that it was generated correctly?

No. A string can have the correct representation, version and variant while still being fabricated, repeated or generated with poor randomness. The inspector cannot determine its source. Nil and Max are recognized special values rather than random identifiers.

UUID Validator and Inspector

Paste a UUID into the inspector shown first on this page. Check the representation separately from the version and variant, copy its canonical form, and read the embedded timestamp of an RFC v7. This does not prove uniqueness or authenticity.

Validate and inspect a UUID

Check the representation, version and variant. For an RFC v7, read the embedded timestamp. This cannot prove uniqueness, origin or authenticity.

UUID

Version 4 · randomReady

Version

How many

Format

Formatting, count, version and a valid namespace can be remembered on this device. Names, generated UUIDs and inspection input are not saved. Page presets preserve remembered choices until you explicitly change each setting.

Common questions

How do I validate a UUID or decode a v7 timestamp?: Paste the value in the inspector. It accepts 32 hexadecimal characters or complete 8-4-4-4-12 groups, optionally enclosed in balanced braces, and accepts upper or lower case. A readable representation is reported separately from a recognized version and variant. Nil and Max have special labels. Only an RFC-variant v7 gets an embedded timestamp display; the timestamp does not prove when or by whom the value was made. V4 has no timestamp to extract.
How many characters and bytes are in a UUID?: A UUID is 128 bits, or 16 bytes. Its canonical hexadecimal text has 36 characters: 32 hexadecimal digits and four dashes. No dashes gives 32 characters; braces add two more. A 16-character or 16-bit value is not a complete UUID. The output download is a UTF-8 text list, not a binary 16-byte UUID file or a shortened-ID encoding.
What are Nil, Max and the UUID variant?: Nil is 00000000-0000-0000-0000-000000000000 and Max is ffffffff-ffff-ffff-ffff-ffffffffffff. They are special all-zero and all-one values. The variant bits identify a UUID layout: this tool generates the RFC variant and names legacy NCS, Microsoft and reserved variants when inspecting a value. A readable string with an unrecognized version or legacy variant is not labelled as a recognized modern layout.
Does a readable UUID prove that it was generated correctly?: No. A string can have the correct representation, version and variant while still being fabricated, repeated or generated with poor randomness. The inspector cannot determine its source. Nil and Max are recognized special values rather than random identifiers.

UUID v4 uses secure browser randomness. UUID v7 includes the device-clock timestamp, a counter and random bits; clock rollback and other tabs are outside its ordering guarantee. UUID v5 follows the SHA-1 namespace/name construction and is deterministic, not secret. Inspection checks representation and layout, not uniqueness or authenticity.