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UUID Generator

Generate random UUIDs (v4) and time-sortable UUIDs (v7) in bulk.

Generated with your browser's crypto API - nothing is sent to a server.

f55106ed-e8d1-4a73-bd90-a36ca7972bdb

UUID Inspector

Paste any UUID to identify its version - v7 UUIDs reveal their embedded creation timestamp.

UUID Format Breakdown

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
  • 4 is the version digit (4 = random, 7 = time-sortable)
  • y is the variant (8, 9, a, or b)
  • In v7, the first 48 bits are a Unix millisecond timestamp, so IDs sort by creation time
  • Total: 128 bits = 32 hex digits + 4 dashes = 36 characters

Code Examples

// Native UUID v4 (modern browsers/Node)
crypto.randomUUID(); // "550e8400-e29b-41d4-a716-446655440000"

// Or using the uuid package
import { v4 as uuidv4 } from 'uuid';
uuidv4(); // "9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d"

Frequently Asked Questions

What's the difference between UUID v4 and v7?

UUID v4 is fully random. UUID v7 (RFC 9562) starts with a 48-bit Unix millisecond timestamp, so v7 IDs sort by creation time - which makes them much friendlier to database indexes than v4. Use v7 for new database keys, v4 when creation time must not leak.

Are UUIDs truly unique?

UUID v4 has 122 random bits, giving 5.3×10^36 possibilities. Collision probability is astronomically low - you'd need to generate 1 billion UUIDs per second for 85 years to have a 50% collision chance.

Should I use UUID or ULID?

UUIDs are more widely supported. ULIDs are sortable by time and slightly shorter. Use UUID for compatibility, ULID when you need time-sortable identifiers.

Related Tools

UUID v7 Generator

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Generate MD5, SHA-1, SHA-256, and SHA-512 hashes from text or files, with optional HMAC keys.

Random Number Generator

Generate random numbers with various options and ranges.

This tool runs entirely in your browser - nothing you enter is uploaded or stored.