UUID Inspector - Parse and Explain UUID / GUID Strings

How to use this tool

1. Paste or choose an example. Enter a UUID in hyphenated or compact hex form, with an optional URN prefix or matching wrapper, or load one of the samples.
2. Read the live result. The inspector identifies the version and variant and shows the fields it can decode. Use Inspect to re-run the current value or Generate v4 to make a new random UUID.
3. Check time and node details. For v1, v6, and v7, compare the embedded timestamp with its Unix-millisecond and local-time views. For v1, v2, and v6, review the node flag before treating the node as a hardware address.

What is a UUID?

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit identifier originally specified in RFC 4122 and updated by RFC 9562 and displayed as five groups of hexadecimal digits separated by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

The M nibble encodes the version and the two most-significant bits of N encode the variant.

UUID versions

UUID versions 6 and 7 are finalized formats in RFC 9562 (May 2024), not drafts. Version 6 reorders the Gregorian timestamp fields for sorting; version 7 starts with a Unix-millisecond timestamp followed by random or generator-defined bits.

Special UUIDs

• Nil UUID: All zeros (00000000-0000-0000-0000-000000000000). Used as a sentinel or default value.
• Max UUID: All ones (ffffffff-ffff-ffff-ffff-ffffffffffff). Defined in RFC 9562 as the highest possible UUID value.

v1 timestamp extraction

Version 1 UUIDs embed a 60-bit timestamp counting 100-nanosecond intervals since 15 October 1582 (the Gregorian calendar epoch). This tool decodes that timestamp and converts it to a human-readable UTC date.

The node field in v1 UUIDs was originally the MAC address of the generating machine. For privacy reasons, modern implementations often substitute a random node value.

v1 MAC address privacy risk

The original UUID v1 specification used the MAC address of the network interface that generated the UUID as the node field (the last 12 hex characters). This exposed the hardware identity of the generating machine, allowing UUIDs to be traced back to a specific computer. This was a significant privacy concern - and one key reason why UUID v4 (fully random) became the dominant version. Modern v1 implementations typically substitute a random node to mitigate this risk.

v7 timestamp extraction

UUID v7 stores a Unix millisecond timestamp in the most significant 48 bits. For a v7 UUID like 018f4a2c-3b00-7abc-8def-123456789abc:

• The first three hyphen-separated groups encode the timestamp: 018f4a2c-3b00 is a 48-bit value.
• Convert to decimal: 0x018f4a2c3b00 = 1,716,812,000,000 ms -> a date in May 2024.

This tool extracts and displays the embedded v7 timestamp automatically.

The inspector also accepts the 32 hexadecimal digits without hyphens, the urn:uuid: prefix, and one matching pair of braces, parentheses, or quotes. It normalizes these forms before showing the same field groups, so values copied from a URN or a compact UUID generator can be inspected directly.

Namespace UUIDs for v3 and v5

UUID v3 (MD5) and v5 (SHA-1) are name-based: they hash a namespace UUID and a name string together to produce a deterministic UUID. The same namespace + name always produces the same UUID. Pre-defined namespace UUIDs from RFC 4122:

• DNS: 6ba7b810-9dad-11d1-80b4-00c04fd430c8
• URL: 6ba7b811-9dad-11d1-80b4-00c04fd430c8
• OID: 6ba7b812-9dad-11d1-80b4-00c04fd430c8
• X.500 DN: 6ba7b814-9dad-11d1-80b4-00c04fd430c8

Example: UUID v5 with the URL namespace and name https://example.com always produces 2ed6657d-e927-568b-95e3-af7ca03ece37. This makes v3/v5 ideal for generating stable, reproducible IDs from known inputs such as content URLs or canonical record keys.