UUIDs (Universally Unique Identifiers) are 128-bit numbers used to uniquely identify information in computer systems. Our free online UUID generator helps you create unique identifiers for your applications, databases, and distributed systems with various customization options.

Why UUIDs Matter

Global Uniqueness

UUIDs are designed to be unique across space and time, making them ideal for distributed systems where coordination between nodes is difficult.

No Central Authority

Unlike sequential IDs that require a central database, UUIDs can be generated independently by any system without coordination.

Database Efficiency

UUIDs work well as primary keys in distributed databases, allowing records to be created independently and merged later.

Security Benefits

Random UUIDs (v4) are unpredictable, making them useful for security tokens, session IDs, and other sensitive applications.

UUID Versions Explained

Version 1 (Time-based)

Combines the current timestamp with a MAC address to create a unique ID. Provides temporal ordering but may reveal information about the generating system.

Version 3 (MD5 Hash)

Generates a UUID by hashing a namespace identifier and a name using MD5. Deterministic - the same inputs always produce the same UUID.

Version 4 (Random)

Uses random or pseudo-random numbers to generate the UUID. Most common version used when uniqueness is the primary requirement.

Version 5 (SHA-1 Hash)

Similar to version 3 but uses the more secure SHA-1 algorithm. Recommended when you need deterministic UUID generation from names.

How to Use This UUID Generator

Select how many UUIDs you need (1-1000)
Choose the appropriate UUID version for your use case
Customize the output format (uppercase, braces, hyphens)
Click "Generate UUIDs"
Copy individual UUIDs or download the entire set
Use in your application, database, or system

UUID Best Practices

Choose the right version - v4 for general use, v1 when you need temporal ordering, v3/v5 for deterministic generation
Consider database performance - UUIDs as primary keys may impact indexing performance compared to sequential IDs
Format consistently - Stick with either uppercase or lowercase throughout your application
Validate inputs - Always verify UUIDs from external sources before processing
Store efficiently - Consider storing as binary (16 bytes) rather than text (36 chars) in databases
Use for distributed systems - UUIDs shine in environments where coordination is difficult

Frequently Asked Questions

What's the difference between UUID and GUID?

GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID standard. They are essentially the same, though GUID sometimes refers specifically to Microsoft's variant.

Are UUIDs really unique?

While theoretically possible to generate duplicates, the probability is extremely low (1 in 2¹²² for v4 UUIDs). For practical purposes, they can be considered unique.

When should I not use UUIDs?

Avoid UUIDs when you need compact identifiers (they're 36 chars as text), when sequential IDs would work better for indexing, or when human readability is important.

Are generated UUIDs stored anywhere?

No. All UUID generation happens in your browser - your UUIDs never leave your device or touch our servers. For maximum security, you can generate UUIDs offline.

Can I customize the namespace for v3/v5 UUIDs?

Our online tool uses standard namespace UUIDs (like DNS). For custom namespaces, you would need to implement UUID generation in your own code.

UUID Generator Tool

Generated UUIDs

About UUIDs (Universally Unique Identifiers)