UUID / GUID Generator
Create UUID v4 identifiers for database keys, correlation IDs, and test fixtures without a central allocator.
Generate batches and copy them in one action when seeding staging environments.
How to use
- Set Number of UUIDs (1–100) and click Generate.
- Use Copy all to copy every UUID (one per line), or Copy next to a single UUID.
- Use Share URL to copy a link that opens the tool with the same count (e.g.
?count=10). - UUIDs are RFC 4122 version 4 (random); safe for IDs, tokens, and database keys.
1Identifiers that collide only in theory
Version 4 UUIDs are random 122-bit values with fixed version bits; the collision probability is low enough that many distributed systems use them as primary keys without a central allocator.
They are not guaranteed sortable by creation time; if you need chronological clustering, databases often provide time-ordered alternatives.
- Use UUIDs when you merge data from multiple devices or services without a single sequence generator.
- Prefer opaque identifiers in public URLs if you want to avoid leaking sequential business volume.
2Formatting and storage
The canonical string includes hyphens for readability; some storage layers strip them to save a few bytes—just stay consistent within one datastore.
When you embed UUIDs in URLs, lowercase hex is the most common convention today, though many parsers accept mixed case.
3Security note
Random UUIDs are not secrets by themselves; do not rely on obscurity of a v4 UUID to protect a private resource without authentication.
If you need unguessable tokens for session identifiers, use a cryptographically secure random generator with enough entropy for your threat model.
4Distributed systems and databases
UUID v4 avoids coordination when creating IDs across microservices or offline clients. Some databases index UUID columns poorly compared to sequential integers—consider ULID or time-ordered IDs if range scans matter.
5Public identifiers
UUIDs in URLs are harder to guess than sequential IDs but are not authentication. Always authorize access server-side regardless of ID format.
6Quick checklist for UUID usage
Use v4 for opaque identifiers; do not assume time ordering. Store UUIDs in a consistent string format (with or without hyphens) per database.
- Index UUID columns appropriately in high-volume tables.
- Do not expose sequential business metrics via guessable IDs alone.
Examples
Single v4 UUID
Use as an opaque primary key in a new table.
550e8400-e29b-41d4-a716-446655440000 (example format)Batch for test fixtures
Generate ten UUIDs to seed integration tests.
Count: 10 → copy all for SQL INSERT or factory data