🆔 UUID Generator
Generate random UUID v4 identifiers. Bulk generation, multiple formats, one-click copy.
About This UUID Generator
What It Does
The UUID Generator creates universally unique identifiers using the UUID version 4 specification. Each UUID is a 128-bit random number, formatted as 32 hexadecimal digits separated by hyphens. The tool generates cryptographically random UUIDs using your browser's Web Crypto API, ensuring each identifier is statistically unique — the chance of a collision is so small that you could generate a billion UUIDs per second for the next century and still likely never see a duplicate.
Features
- Generate 1 to 100 UUIDs in a single click
- Four output formats: standard (dashes), no dashes, UPPERCASE, and {braced}
- One-click copy all generated UUIDs to clipboard
- Uses crypto.getRandomValues() for true randomness
- UUID v4 compliant — bits 13 and 17 are set according to RFC 9562
Common Use Cases
Developers use UUIDs as primary keys in database tables when auto-incrementing integers aren't suitable — especially in distributed systems where multiple servers need to generate IDs without coordination. They're used as session tokens, file identifiers, API request IDs for tracing, temporary filenames in upload pipelines, and unique keys in key-value stores. Data engineers generate batches of UUIDs for test data seeding and ETL job identifiers.
Tips
The "no dashes" format is useful for systems that don't accept hyphens in identifiers. UPPERCASE format matches the convention used by some Microsoft and Oracle systems. The braced format {xxxxxxxx-xxxx-...} is occasionally required by Windows registry entries and COM interfaces. For database primary keys, the standard dashed format is the most widely compatible across PostgreSQL, MySQL, and SQLite.
FAQ
Can two UUIDs ever be the same?
Theoretically possible but practically impossible. With 122 random bits in UUID v4, you'd need to generate about 2.7 × 10^18 UUIDs to have a 50% chance of a single collision. That's 2.7 quintillion — billions of years of generation at any realistic rate.
What's the difference between UUID and GUID?
They're the same thing. Microsoft uses the term GUID (Globally Unique Identifier), while the rest of the industry uses UUID (Universally Unique Identifier). The format and generation are identical.
Should I use UUIDs as database primary keys?
It depends. UUIDs are great for distributed systems and when you need to generate IDs client-side, but they take more storage (16 bytes vs 4-8 for integers) and can cause index fragmentation in B-tree databases like MySQL/InnoDB. PostgreSQL handles them well with its native UUID type.
What does version 4 mean?
UUID has several versions. Version 4 is purely random — the most common and widely used. Version 1 uses timestamps and MAC addresses (privacy concern). Version 3 and 5 are name-based (deterministic, generated from a namespace and name). Version 4 is what almost everyone means when they say "UUID."