UUID Generator — Free Online UUID v4 Generator | GadgetSurge

About UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit identifier standardised by RFC 4122. It is formatted as 32 hexadecimal digits separated by hyphens in the pattern 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are designed to be unique across all devices and all time without requiring a central authority to assign them.

This generator creates UUID version 4, which uses cryptographically secure random numbers. The probability of two UUID v4 values colliding is so astronomically small that it is effectively impossible — you would need to generate over a billion UUIDs per second for 85 years before a 50% chance of collision.

UUIDs are the standard choice for database primary keys in distributed systems, where auto-incrementing integers would require coordination between servers. They are also widely used as session IDs, request IDs for API tracing, file names for uploaded content, and idempotency keys.

All UUIDs are generated using the Web Crypto API (crypto.getRandomValues), which provides cryptographically strong random values in the browser without any server interaction.

How to Use UUID Generator

1. Click "Generate UUID" to create a new random UUID v4.
2. Click again to generate another, or set a quantity to generate multiple at once.
3. Copy individual UUIDs with the Copy button, or copy all at once.
4. Use the generated UUIDs as database primary keys, session IDs, or unique identifiers in your application.

Common Use Cases

• Database primary keys: Use UUIDs as primary keys in PostgreSQL, MySQL, MongoDB, or any database to avoid sequential ID prediction and enable distributed writes without coordination.
• Session and token IDs: Generate unique session identifiers for user authentication tokens, CSRF tokens, and API keys.
• API request tracing: Attach a UUID to each API request as an X-Request-ID header to trace requests through microservices and correlate logs.
• File upload naming: Use UUIDs as filenames for user-uploaded content to prevent collisions and avoid exposing sequential file counts.
• Idempotency keys: Generate UUIDs as idempotency keys for payment APIs and other services that need to safely retry requests without double-processing.
• Testing and mocking: Generate batches of UUIDs to populate test databases, mock API responses, or seed development data.

Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal characters separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. It is standardised by RFC 4122 and designed to be unique across all computers and all time without central coordination.

What is the difference between UUID v1, v4, and v7?

UUID v1 is based on the current timestamp and MAC address — it is time-ordered but leaks hardware information. UUID v4 uses entirely random numbers — it is the most widely used version and recommended for most use cases. UUID v7 is a newer standard that uses random numbers with a time-ordered prefix, making it better for database indexing than v4.

Are UUIDs truly unique?

UUID v4 is generated from 122 random bits. The probability of generating two identical UUIDs is 1 in 5.3 × 10³⁶. In practice, UUID collisions essentially never happen — even generating millions of UUIDs per second would take billions of years to produce a collision.

Can UUIDs be used as database primary keys?

Yes, and this is one of the most common use cases. UUIDs as primary keys allow records to be created on any server without coordination, prevent ID enumeration attacks, and make data merging from different databases straightforward. The tradeoff is slightly larger storage than integers and less optimal index performance for UUID v4 (UUID v7 addresses this with time-ordering).

Are the generated UUIDs cryptographically secure?

Yes. This generator uses the Web Crypto API (window.crypto.getRandomValues), which provides cryptographically strong random values. These are suitable for use as session tokens and security-sensitive identifiers.

What is a GUID? Is it the same as a UUID?

GUID (Globally Unique Identifier) is Microsoft's name for the UUID standard. GUIDs and UUIDs are the same format and fully interchangeable. Microsoft tools typically display them in uppercase with braces: {550E8400-E29B-41D4-A716-446655440000}.