UUID Generator

What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier designed to be unique across all systems without central coordination. UUIDs appear as 36-character strings formatted with hyphens, like: 550e8400-e29b-41d4-a716-446655440000.

The design ensures that identifiers generated independently on different computers at different times are virtually guaranteed to be unique. This makes UUIDs ideal for distributed systems where centralized ID assignment is impractical.

This free UUID generator creates valid identifiers instantly using your browser's cryptographic random number generator, providing secure, standardized identifiers for any application.

How to Generate UUIDs Online

Creating UUIDs is instant with this simple tool:

1. Click the generate button to create a new UUID immediately.

2. View your UUID displayed in the standard format with four hyphens separating five groups of hexadecimal characters.

3. Use the copy button to transfer the UUID to your clipboard.

4. Generate additional UUIDs as needed - each one is independent and unique.

The generator creates Version 4 UUIDs, which use random numbers for all significant bits, providing maximum uniqueness and unpredictability.

UUID Versions Explained

The UUID specification defines several versions with different generation methods:

Version 1 uses timestamps and MAC addresses. These UUIDs based on time and hardware can reveal information about when and where they were created.

Version 3 generates deterministic UUIDs from namespace identifiers and names using MD5 hashing. The same inputs always produce the same UUID.

Version 4 uses random or pseudo-random numbers for nearly all bits. This is the most common version for general-purpose unique identifiers.

Version 5 works like Version 3 but uses SHA-1 hashing instead of MD5, providing stronger uniqueness guarantees for namespace-based generation.

This tool generates Version 4 UUIDs, identifiable by the digit 4 in the third group and the digit 8, 9, a, or b starting the fourth group.

Common Uses for UUIDs

UUIDs serve essential functions across software development:

Database primary keys using UUIDs avoid collision issues when merging data from multiple sources or shards.

Session identifiers use UUIDs to track user sessions with tokens that are virtually impossible to guess.

File naming with UUIDs prevents conflicts when multiple systems upload files to shared storage.

API request tracking uses UUIDs to correlate logs across distributed microservices handling the same request.

Message queues identify individual messages with UUIDs for reliable processing and deduplication.

Temporary resource identifiers use UUIDs for objects that need unique names but only exist briefly.

Configuration and deployment systems use UUIDs to identify specific runs, builds, or environment instances uniquely.

UUID Format and Structure

Understanding UUID structure helps verify and work with identifiers correctly:

Length is always 36 characters: 32 hexadecimal digits plus 4 hyphens in a standard format.

Format follows the pattern: 8-4-4-4-12, meaning groups of 8, 4, 4, 4, and 12 hexadecimal characters separated by hyphens.

Case is technically insignificant but lowercase is conventional. Both 550e8400 and 550E8400 represent the same value.

Hyphens are optional in storage but conventional in display. Some systems store UUIDs without hyphens to save space.

The probability of collision with random Version 4 UUIDs is astronomically low. You would need to generate billions of UUIDs before having a meaningful chance of duplicates.