UUID Generator

UUID Generator – Create Universally Unique Identifiers

A UUID (Universally Unique Identifier) — also known as GUID (Globally Unique Identifier) on Windows — is a 128-bit number used to uniquely identify information in distributed systems. When generated properly, the probability of collision is effectively zero for any practical purpose.

UUID Versions Explained

UUID v1 (Time-based):

Generated using the current timestamp and MAC address. Contains embedded time information. Useful for time-sorted records but reveals system information.

UUID v4 (Random):

Generated using cryptographically secure random numbers. The most widely used version. No information about generation time or machine is embedded.

UUID v5 (Name-based SHA-1):

Deterministically generated from a namespace and name. The same inputs always produce the same UUID. Useful for content-based addressing.

Where Are UUIDs Used?

• Database primary keys: Allows distributed ID generation without a central counter.
• REST APIs: Resource identifiers in URLs and responses.
• File systems: Temporary file names, cache keys.
• Session tokens: User session identifiers.
• Event tracking: Unique event IDs for analytics.
• Software licensing: Product activation keys.

UUID Structure

A UUID in standard form looks like: 550e8400-e29b-41d4-a716-446655440000. It contains 32 hexadecimal digits displayed in 5 groups separated by hyphens: 8-4-4-4-12 format. Total: 128 bits = 2^122 possible random values for v4.