How to Generate UUIDs for Database Keys and APIs
To generate UUIDs for database keys and APIs, use an online UUID generator that creates version 4 UUIDs instantly. Our UUID Generator generates random UUIDs with one click, and you can generate multiple at once.
What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by the Open Software Foundation. UUIDs are designed to be unique across space and time — no two UUIDs should ever be the same, even if generated on different systems.
Example UUID: 550e8400-e29b-41d4-a716-446655440000
UUIDs are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12.
UUID v4 vs Other Versions
| Version | Generation Method | Best For |
|---|---|---|
| UUID v1 | Time-based + MAC address | Distributed systems needing ordering |
| UUID v4 | Random (most common) | General purpose, primary keys |
| UUID v5 | Namespace + name (SHA-1) | Generating the same UUID from the same input |
| UUID v7 | Time-ordered random | Database performance, MySQL 9+ |
UUID v4 is the most widely used version. It generates random identifiers with approximately 122 bits of randomness — the chance of collision is effectively zero.
Why Use UUIDs for Database Keys
- Global uniqueness — no collisions across systems or databases
- Decentralized generation — any server can generate IDs without coordination
- Merging friendly — merge databases without key conflicts
- Security — UUIDs are unpredictable (unlike sequential integers)
- Distributed systems — microservices can generate IDs independently
- Client-side generation — generate IDs before sending to the database
UUID vs Auto-Increment IDs
| Feature | Auto-Increment ID | UUID |
|---|---|---|
| Uniqueness | Single database only | Global |
| Size | 4 bytes (int) or 8 bytes (bigint) | 16 bytes (128 bits) |
| Readable | Yes (1, 2, 3…) | No (550e8400-…) |
| Merge friendly | No | Yes |
| Predictable | Yes | No |
| Performance | Faster (smaller index) | Slower (larger index) |
| URL safe | Yes | Yes (with dashes) |
How to Generate UUIDs Online (Step-by-Step)
- Open the UUID Generator tool
- Click “Generate” to create a single UUID
- Use “Generate Multiple” to create a batch (up to 100)
- Click “Copy” next to any UUID to copy it
- Use the copied UUID in your code or database
Options
- Uppercase — format UUIDs in uppercase
- Without dashes — remove hyphens for compact storage
- Batch count — generate multiple UUIDs at once
- Copy all — copy all generated UUIDs as a list
FAQ
Are UUIDs truly unique?
UUID v4 has 122 bits of randomness. The probability of collision is approximately 2.71 × 10^-18. In practical terms, you would need to generate billions of UUIDs per second for centuries to have a meaningful chance of collision.
Can two systems generate the same UUID?
The probability is astronomically low. UUID v4 uses cryptographically strong random number generation, making collisions virtually impossible without generating billions of identifiers.
Should I use UUIDs for primary keys?
UUIDs work well as primary keys in distributed systems. For single-server databases, auto-increment integers may perform better due to their smaller size. Consider using UUID v7 for better database performance.
Can I store UUIDs without dashes?
Yes. The non-dashed format (32 hex characters) stores in 32 bytes as a string or 16 bytes as binary. Remove dashes for compact storage; add them back when displaying.
Are UUIDs secure?
UUID v4 is suitable for most use cases. For security-critical applications (password reset tokens, session IDs), use cryptographically secure random values.
Try our free UUID Generator tool to create unique identifiers for your databases, APIs, and distributed systems.