Validation & introspection
UUID analyzer
Paste any UUID to see what is inside it — version, variant, embedded timestamp, entropy, and the node field that can make v1 identifiers traceable to a machine.
Field breakdown
Each byte in hexadecimal.
Details
Equivalent formats
The same 128 bits, written in other ways. Useful when a system expects a specific representation.
Reference
Where each piece lives
A UUID is 128 bits, written in five hyphen-separated groups. Which groups carry meaning depends on the version — the same 36 characters can be opaque in v4 and revealing in v1.
time_low
Bits 0–31Low bits of the timestamp in v1; random in v4.
time_mid
Bits 32–47Middle bits of the v1 timestamp.
time_high / version
Bits 48–59 + 4The version nibble sits in the high 4 bits of octet 6 — the 13th character.
clock_seq
Bits 60–73Random per node; guards against a repeated timestamp.
node
Bits 74–127A machine identifier in v1 — historically the MAC address. This is why v1 can expose information.
variant
Bits top 2–3 of octet 810 means RFC 9562. Anything else is legacy or reserved.
| Field | Bits | Meaning |
|---|---|---|
| time_low | 0–31 | Low bits of the timestamp in v1; random in v4. |
| time_mid | 32–47 | Middle bits of the v1 timestamp. |
| time_high / version | 48–59 + 4 | The version nibble sits in the high 4 bits of octet 6 — the 13th character. |
| clock_seq | 60–73 | Random per node; guards against a repeated timestamp. |
| node | 74–127 | A machine identifier in v1 — historically the MAC address. This is why v1 can expose information. |
| variant | top 2–3 of octet 8 | 10 means RFC 9562. Anything else is legacy or reserved. |
Why v1 can expose information
The node field can contain a hardware address. Two v1 UUIDs from the same machine may share it, making them linkable to each other and potentially to that machine. The analyzer shows this field explicitly.
Why v7 exists
A 48-bit millisecond timestamp leads the value, so UUIDs sort in generation order. That helps a B-tree index stay orderly as rows are inserted.
Why v5 instead of v3
Both are name-based and deterministic. v3 uses MD5, which is no longer considered secure; v5 uses SHA-1 and is the modern choice for name-based UUIDs.