UUID Generator
Generate RFC 4122 compliant UUIDs (Universally Unique Identifiers) in multiple versions. Cryptographically secure, instant generation with bulk support.
Generate UUID
Select UUID version and customize options
Generated UUIDs
Click "Generate UUIDs" to create unique identifiers
Analyze & Validate a UUID
Paste any UUID to verify its format, decode its version, variant and embedded timestamp
Accepts uppercase, lowercase, no hyphens, {braces} and urn:uuid: prefixes.
Frequently Asked Questions
Which UUID versions can I create?
Version 1 (time-based), version 4 (random), version 5 (namespace and name), version 7 (time-ordered random) and the special nil UUID, plus parsing and validation of existing values.
Are the UUIDs cryptographically secure?
Yes. Random-based versions draw from a cryptographically secure source, suitable for identifiers that must not be guessed.
Can I generate many at once?
Yes. Bulk mode creates a whole batch in one click, with copy and export for scripts and seeds.
Could two generated UUIDs collide?
For all practical purposes no. A random UUID has 122 bits of entropy, making accidental duplicates astronomically unlikely.
What format do the generated UUIDs use?
Each UUID is exactly 36 characters long: 32 hexadecimal digits grouped into five hyphen-separated sections following the 8-4-4-4-12 pattern, such as 3f2504e0-4f89-41d3-9a0c-0305e82c3301. Output is lowercase, ready to paste into code, config files, or database records without trimming.
Can I copy the generated UUIDs or download them as a file?
Yes. Click any single UUID to copy it instantly, or use the copy-all button to grab the whole list at once. Bulk results can also be downloaded as a plain text file with one UUID per line, ready for code, spreadsheets, or test fixtures.
Are my generated UUIDs stored or sent anywhere?
Generation runs entirely in your browser using your device's randomness source, so no identifiers or inputs are transmitted to a server. Once the page has loaded, you can keep generating offline, and every UUID stays private on your own computer.
Can I use these UUIDs as database primary keys?
Yes. UUID v4 works as a primary key in PostgreSQL, MySQL, MongoDB, and most ORMs because values are unique across systems. For very large tables, prefer UUID v7: its time-ordered digits reduce B-tree index fragmentation and speed up batch inserts.
Understanding UUID Versions
Choose the right UUID version for your specific use case
UUID v1 (Time-based)
Generated from the current timestamp and MAC address. Provides uniqueness across space and time.
UUID v4 (Random)
Generated using cryptographically secure random numbers. Most commonly used version.
UUID v5 (Name-based)
Generated from a namespace and name using SHA-1 hashing. Produces consistent UUIDs for the same input.
UUID v7 (Time-ordered)
Generated from Unix timestamp with millisecond precision. Sortable by creation time.
UUID Format (RFC 4122)
A UUID is 128 bits written as 32 hexadecimal digits in five groups — 8-4-4-4-12 — separated by hyphens
The five segments
- time_low
- 8 hex · low 32 bits of the timestamp (v1) or random data
- time_mid
- 4 hex · middle 16 bits of the timestamp
- time_hi_and_version
- 4 hex · version nibble + high 12 bits of the timestamp
- clock_seq
- 4 hex · variant bits + clock sequence
- node
- 12 hex · 48-bit node ID (MAC in v1) or random data
v4 collision probability
A random v4 UUID has 122 random bits — about 5.3 × 10³⁶ possible values:
| UUIDs generated | Collision chance |
|---|---|
| 10³ | ~10⁻⁵⁴ |
| 10⁶ | ~10⁻³¹ |
| 10⁹ | ~10⁻¹⁰ |
| 2.7 × 10¹⁸ | 50% |
Edge cases developers hit
All of these forms appear in real systems — know them before you validate
{550e8400-e29b-41d4-a716-446655440000}
Some systems (Microsoft COM, .NET ToString("B")) wrap UUIDs in braces. Strip them before validating.
urn:uuid:550e8400-e29b-41d4-a716-446655440000
The URN form is valid in RDF and XML documents. Strip the urn:uuid: prefix before parsing.
550E8400-E29B-41D4-A716-446655440000
Hex is case-insensitive. PostgreSQL lowercases, SQL Server uppercases by default — normalize before comparing.
550e8400e29b41d4a716446655440000
The 32-digit form without hyphens is common in APIs and databases. Re-insert hyphens at 8-4-4-4-12 to display.
00000000-0000-0000-0000-000000000000
The Nil UUID is special: all zeros, still 36 characters. Often means "no value" — treat it as null in business logic.
v7: 01890d8f-5ce0-7a5b-9a4a-a4fa5f5e6a72
UUID v7 embeds a Unix millisecond timestamp — sort a v7 column and rows come out in creation order.
Technical Specifications
Our UUID generator uses industry-standard algorithms and security practices
Security Features
- RFC 4122 compliant generation
- Cryptographically secure randomness (Web Crypto API)
- Client-side generation only
- Practically unique collision resistance
Customization Options
- Multiple UUID versions (v1, v4, v5, v7, Nil)
- Bulk generation (up to 100)
- Uppercase and no-dash formats
- Instant copy and download
References & Resources
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RFC 9562 - UUIDs and ULIDs (IETF)
The IETF standard defining UUID versions, formats, and generation algorithms.
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Universally Unique Identifier - Wikipedia
General reference on universally unique identifiers and their variants.