Free online UUID generator - Generate v1, v3, v4, v5 UUIDs with custom formatting
Privacy-first
Generated locally in browser
Multiple versions
v1, v3, v4, v5 UUID support
Format options
Standard, URN, braces & more
Click "Generate New" to create UUIDs
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. The probability of generating duplicate UUIDs is so low that they can be considered unique for practical purposes.
v1 uses timestamp and MAC address, v3 uses MD5 hashing of a namespace/name, v4 uses random or pseudo-random numbers (most common), and v5 uses SHA-1 hashing of a namespace/name. v4 is recommended for most use cases as it doesn't leak information about when or where it was generated.
Use v4 for general purposes (random IDs), v1 when you need chronological sorting (but be aware it exposes MAC address), v3/v5 when you need deterministic IDs from a namespace and name (v5 preferred over v3). Most applications use v4.
While not mathematically guaranteed to be unique, the probability of generating duplicate UUIDs is negligible. For v4 UUIDs, you'd need to generate billions of UUIDs before having a meaningful chance of collision. They're considered unique for all practical purposes.
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. The probability of generating duplicate UUIDs is so low that they can be considered unique for practical purposes.
v1 uses timestamp and MAC address, v3 uses MD5 hashing of a namespace/name, v4 uses random or pseudo-random numbers (most common), and v5 uses SHA-1 hashing of a namespace/name. v4 is recommended for most use cases as it doesn't leak information about when or where it was generated.
Use v4 for general purposes (random IDs), v1 when you need chronological sorting (but be aware it exposes MAC address), v3/v5 when you need deterministic IDs from a namespace and name (v5 preferred over v3). Most applications use v4.
While not mathematically guaranteed to be unique, the probability of generating duplicate UUIDs is negligible. For v4 UUIDs, you'd need to generate billions of UUIDs before having a meaningful chance of collision. They're considered unique for all practical purposes.