UUID Generator
Generate random v4 or time-ordered v7 UUIDs in bulk, straight in your browser. Choose how many you need and the format, copy a single line or the whole batch, and inspect any UUID you paste.
- Free
- No sign-up
- No ads
Inspect a UUID
Paste any UUID to see its version and variant, and when a v1, v6 or v7 UUID was created.
NIL UUID
The reserved all-zero UUID, handy as a placeholder or a "no value" marker.
00000000-0000-0000-0000-000000000000UUID versions
Every UUID is 32 hexadecimal digits shown in five groups as 8-4-4-4-12. The 13th digit marks the version and the first digit of the fourth group encodes the variant (8, 9, a, or b for the common variant).
| Version | Description |
|---|---|
| Version 1 | Time-based, built from a timestamp and the host MAC address. |
| Version 3 | Name-based: an MD5 hash of a namespace and a name. |
| Version 4 | Random. Every digit except the version and variant is random. This tool generates it. |
| Version 5 | Name-based, like v3 but using a SHA-1 hash. |
| Version 6 | Version 1 with the timestamp reordered so IDs sort by time. |
| Version 7 | A Unix millisecond timestamp followed by random bits, so IDs sort by creation time. This tool generates it. |
| Version 8 | Custom layout for vendor-specific data, defined only by its version and variant bits. |
UUIDs, explained
What is a UUID?+
A UUID (universally unique identifier) is a 128-bit value written as 36 characters, for example 3f2504e0-4f89-41d3-9a0c-0305e82c3301. It is designed to be unique across space and time without a central authority, so it is ideal for database keys, request IDs, and file names.
What is a version 4 UUID?+
A version 4 UUID is generated almost entirely from random data. The 13th character is always 4 (the version) and the 17th is one of 8, 9, a, or b (the variant). This tool creates v4 UUIDs using your browser’s cryptographic random generator.
Should I use UUID v4 or v7?+
Use v7 for database primary keys and anything you want to sort by creation time. Its first 48 bits are a millisecond timestamp, so new rows land at the end of an index instead of at random spots, which keeps inserts fast. Use v4 when the ID should reveal nothing, not even roughly when it was made.
Are these UUIDs random and safe to use?+
Yes. The random bits come from crypto.randomUUID or crypto.getRandomValues, the same cryptographically secure source used for keys and tokens. Nothing is generated on a server and nothing you create is ever uploaded.
What is the NIL UUID?+
The NIL UUID is the all-zero value 00000000-0000-0000-0000-000000000000. It is a valid, reserved UUID used as a placeholder or a "no value" marker, similar to null. You can copy it from the reference card above.
Should I use uppercase or lowercase UUIDs?+
The standard form is lowercase, and most systems output lowercase. UUIDs are case-insensitive when compared, so uppercase is only a display preference. Use the uppercase toggle if your platform expects it, and the format menu for the no-hyphen, {braces} or urn:uuid: forms.
Related tools
All tools →More in General Tools.
Need something custom built?
The studio behind this free tool builds custom bots, game servers and websites.