Developer UUID tools
Nil UUID
The Nil UUID is the all-zero UUID value. Use it carefully as a sentinel value only when your protocol, schema, or code explicitly expects it.
Nil UUID value
The Nil UUID is the all-zero UUID used as a sentinel value in some protocols, schemas, and tests.
00000000-0000-0000-0000-000000000000
Nil UUID vs null vs empty string
The Nil UUID is a real UUID value where every bit is zero. Null means no value. An empty string is text with length zero and is not a UUID.
Do not use the Nil UUID as a casual replacement for missing data unless the system explicitly documents that behavior.
When Nil UUID appears
You may see the Nil UUID in tests, default fixtures, protocol examples, placeholder database rows, or APIs that need a sentinel UUID-shaped value.
Validate the Nil UUID
The Nil UUID has valid UUID shape but no version digit. A validator should identify it separately instead of reporting it as UUID v4 or UUID v7.
FAQ
What is the Nil UUID?+
The Nil UUID is 00000000-0000-0000-0000-000000000000, where all UUID bits are zero.
Is Nil UUID the same as null?+
No. Null means absent value. Nil UUID is an explicit all-zero UUID value.
Is an empty UUID string valid?+
No. An empty string is not a UUID. Use a validator when accepting external values.