UUID Generator
Generate random UUID v4 identifiers. Click to copy, bulk generate, or choose your preferred format.
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Free Online UUID/GUID Generator
Generate universally unique identifiers (UUIDs) version 4, also known as GUIDs (Globally Unique Identifiers). UUID v4 uses random numbers to generate identifiers that are statistically guaranteed to be unique — the probability of generating two identical UUIDs is astronomically small (1 in 2^122).
UUID Format
A standard UUID v4 looks like: 550e8400-e29b-41d4-a716-446655440000. It consists of 32 hexadecimal digits displayed in five groups separated by hyphens, in the pattern 8-4-4-4-12. The version number (4) is encoded in the third group, and the variant bits are in the fourth group.
Common Use Cases
Database primary keys (especially in distributed systems), API request identifiers, session tokens, file naming to avoid conflicts, message queue identifiers, correlation IDs for logging and tracing, and temporary file or resource identifiers. UUIDs are widely used in software development because they can be generated independently on any machine without coordination.
Frequently Asked Questions
They are essentially the same thing. UUID (Universally Unique Identifier) is the official term used in RFC 4122. GUID (Globally Unique Identifier) is Microsoft's terminology for the same concept. Both refer to 128-bit identifiers in the same format.
Statistically yes. UUID v4 uses 122 random bits, giving 5.3 × 10^36 possible values. The probability of generating a duplicate is negligible — you'd need to generate 2.71 quintillion UUIDs to have a 50% chance of one collision.
Yes. UUIDs are commonly used as primary keys in PostgreSQL (uuid type), MySQL (CHAR(36) or BINARY(16)), MongoDB, and other databases. They're especially useful in distributed systems where multiple servers need to generate IDs independently.