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UUID Generator
Generate UUID v4 (random) and v7 (timestamp-based). Bulk generation, format options, and validation. Everything runs in your browser.
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What is a UUID?
A UUID (Universally Unique Identifier), also known as GUID (Globally Unique Identifier), is a 128-bit identifier that is practically unique across space and time. UUIDs are formatted as 32 hexadecimal characters separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
With UUID v4, the probability of generating a duplicate is astronomically low — you'd need to generate ~2.71 quintillion (2.71×10¹⁸) UUIDs to have a 50% chance of collision.
UUID v4 vs v7
| Feature | UUID v4 | UUID v7 (RFC 9562) |
|---|---|---|
| Source | 122 random bits | 48-bit timestamp + 74 random bits |
| Sortable | No | Yes (time-ordered) |
| Database index | Poor (random distribution) | Excellent (sequential inserts) |
| Contains timestamp | No | Yes (ms precision) |
| Best for | General purpose, max randomness | Databases, distributed systems, event IDs |
When to Use UUIDs
- Database primary keys — Avoid sequential IDs that expose record count. UUID v7 is ideal for databases.
- Distributed systems — Generate IDs without central coordination. No ID collisions across services.
- API request IDs — Track requests across microservices with unique correlation IDs.
- File names — Unique temporary file names without collision risk.
- Session tokens — Though purpose-built token generators (like secure random strings) are often better for auth tokens.
Generating UUIDs from the Command Line
# Linux uuidgen # v4 cat /proc/sys/kernel/random/uuid # v4 # macOS uuidgen # v4 (uppercase) uuidgen | tr '[:upper:]' '[:lower:]' # lowercase # Python python3 -c "import uuid; print(uuid.uuid4())" # Node.js node -e "console.log(crypto.randomUUID())" # Generate multiple for i in $(seq 10); do uuidgen; done