UUID Generator
Generate random version-4 UUIDs (GUIDs) in bulk, with formatting options — copy or download them.
Nil UUID: 00000000-0000-0000-0000-000000000000 — used to represent an absent or placeholder value.
How to use the UUID Generator
- Choose how many UUIDs you need.
- Toggle formatting options — uppercase, hyphens, braces or quotes.
- Click Generate.
- Copy a single UUID, Copy all, or Download them as a .txt file.
Examples
| Input | Output | Notes |
|---|---|---|
1 UUID, default format | 3f2504e0-4f89-41d3-9a0c-0305e82c3301 | Lowercase, hyphenated (RFC 4122 canonical form). |
uppercase, no hyphens | 3F2504E04F8941D39A0C0305E82C3301 | |
braces (Microsoft GUID style) | {3f2504e0-4f89-41d3-9a0c-0305e82c3301} |
What UUIDs are for
A UUID lets independent systems create identifiers without coordinating. Databases use them as primary keys so records can be generated offline or merged without clashing; APIs use them for request and resource IDs; file systems and message queues use them to name things uniquely.
Anatomy of a v4 UUID
| Part | Example | Meaning |
|---|---|---|
| time_low | 3f2504e0 | Random |
| time_mid | 4f89 | Random |
| time_hi_and_version | 41d3 | Starts with 4 = version 4 |
| clock_seq | 9a0c | First digit 8, 9, a or b = variant 1 |
| node | 0305e82c3301 | Random |
Formatting variants
- Canonical — lowercase with hyphens (the RFC 4122 standard)
- No hyphens — compact 32-char form for URLs and filenames
- Braces —
{…}, common in Windows / .NET - Uppercase — some legacy systems expect it
Related tools
Need a random secret instead of an identifier? Use the Password Generator. For random numbers, see the Random Number Generator.
Frequently asked questions
What is a UUID?
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in the pattern 8-4-4-4-12. It is used as an identifier that can be generated anywhere without a central authority and still be practically unique.
What is a version-4 UUID?
A version-4 UUID is generated from random (or pseudo-random) numbers, with 6 bits fixed to mark the version and variant. This tool uses your browser's cryptographically secure random source, so the values are suitable for real identifiers.
How unique are they really?
There are 2^122 possible v4 UUIDs. You would need to generate about 1 billion per second for 85 years to have a 50% chance of a single collision, so for practical purposes they are unique.
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier. Microsoft tooling often wraps it in braces, which you can enable above.
Are the UUIDs generated on a server?
No. Generation happens entirely in your browser using the Web Crypto API. Nothing is sent anywhere, so the values are yours alone.
What is the nil UUID?
The nil UUID is all zeros (00000000-0000-0000-0000-000000000000). It is a special value meaning "no UUID" — a placeholder for an unset or unknown identifier.