UUID Generator
Generate RFC 4122 UUIDs in v1, v4, or v5 format. Options for quantity, uppercase, and hyphen formatting.
dbb13581-fe71-4e64-87e5-6e998d80e6894a99d84a-3abb-4b56-ae37-2ccea98d152db0d76625-17aa-4848-911a-1fc50a4234222a2586f8-7852-4b38-900e-633a389f1175fdc9f61b-adac-443b-9789-d6f994507c9dExample UUID v4
550e8400-e29b-41d4-a716-446655440000
Format: 8-4-4-4-12 hexadecimal characters
How to use this tool
- Choose a UUID version: v4 (random) is the most widely used.
- Set how many UUIDs you need using the slider (up to 50).
- Toggle UPPERCASE or remove hyphens if your system requires it.
- Click Generate, then copy individual UUIDs or all at once.
UUID versions: randomness, time, and namespaces
v4 is random (RFC 4122); v1 is time/MAC-derived (privacy concerns on some networks); v5 hashes a namespace + name. Choose v4 for opaque IDs unless you need sortable time proximity.
Database uniqueness still needs constraints—collision probability is tiny but not a substitute for transactional checks.
Related tools
These free tools pair well with this page — open them in a new tab to finish your workflow.
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. It is represented as 32 hexadecimal digits grouped as 8-4-4-4-12.
What is the difference between UUID versions?
UUID v1 uses the current timestamp and MAC address. UUID v4 uses random numbers and is the most commonly used version. UUID v4 is recommended unless you specifically need time-based ordering (v1) or name-based determinism (v3/v5).
Are UUIDs truly unique?
UUID v4 has 122 random bits, giving 2¹²² possible values (~5.3 × 10³⁶). The probability of generating a duplicate is negligibly small for all practical purposes.
Can I use UUIDs as database primary keys?
Yes, UUIDs are widely used as primary keys, especially in distributed systems where auto-increment integers could conflict. Note that random UUIDs (v4) can cause index fragmentation in some databases.
Are UUIDs case-sensitive?
No. UUID representations are case-insensitive. Both uppercase and lowercase hex digits are valid and equivalent.
Is it safe to generate UUIDs in the browser?
Yes. This tool uses the browser's built-in crypto.randomUUID() or a cryptographically secure random number generator, so the output is suitable for production use.