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Free Online UUID Generator - v1, v4, v5

Generate universally unique identifiers (UUIDs) instantly with our free online UUID generator. Create RFC 4122 compliant UUIDs in versions 1 (timestamp-based), 4 (random), or 5 (name-based SHA-1). Perfect for database primary keys, API development, session tokens, and distributed systems. Supports bulk generation (up to 1000 UUIDs), multiple output formats (standard, braces, brackets, C array, Base64), uppercase/lowercase options, and one-click copying. All generation happens securely in your browser using cryptographically secure random numbers. No server communication, no data collection, no installation required.

UUID Version Guide

Version 4 (Random): Most commonly used. Generated using random numbers. Collision probability is extremely low (1 in 2^122).
Version 1 (Timestamp): Based on current timestamp and MAC address. Useful when you need time-ordered UUIDs.
Version 5 (Name-based SHA-1): Deterministic UUID generated from a namespace and name. Same input always produces the same UUID.
NIL UUID: Special UUID with all zeros (00000000-0000-0000-0000-000000000000).
MAX UUID: Special UUID with all ones (ffffffff-ffff-ffff-ffff-ffffffffffff).

Powerful UUID Generation Features

Generate UUID v1 (timestamp-based) for chronological ordering

Create UUID v4 (random) with cryptographically secure randomness

Generate UUID v5 (name-based SHA-1) for deterministic identifiers

Bulk generation up to 1000 UUIDs at once

Multiple output formats: standard, braces, brackets, quoted, C array, Base64

Uppercase/lowercase and hyphen removal options

One-click copy individual or all UUIDs to clipboard

Download UUIDs as text file for batch operations

NIL and MAX UUID generation for special use cases

Keyboard shortcuts (Ctrl+Enter) for fast workflow

100% browser-based with cryptographically secure generation

No data sent to servers - complete privacy

What is a UUID Generator?

A UUID (Universally Unique Identifier) generator is an essential tool for developers, database administrators, and system architects who need to create unique identifiers for records, sessions, files, or distributed systems. Our free online UUID generator creates RFC 4122 compliant UUIDs instantly in your browser without any server communication.

UUID Versions Explained

UUID Version 4 (Random)

UUID v4 is the most widely used version, generating completely random 128-bit identifiers. It uses cryptographically secure random number generation, ensuring unpredictability and security. With a collision probability of approximately 1 in 2^122, UUID v4 is perfect for database primary keys, API tokens, session identifiers, and file names.

UUID Version 1 (Timestamp-based)

UUID v1 generates identifiers based on the current timestamp and MAC address. These UUIDs are chronologically sortable, making them ideal for time-series data, event logging, and scenarios where temporal ordering matters. However, v1 UUIDs can reveal information about when and where they were generated, so they're less suitable for public-facing identifiers.

UUID Version 5 (Name-based SHA-1)

UUID v5 is deterministic, generating the same UUID for the same namespace and name combination. This makes it perfect for creating consistent identifiers from URLs, email addresses, domain names, or any string-based data. V5 uses SHA-1 hashing to ensure uniqueness while maintaining reproducibility.

Common Use Cases for UUIDs

UUID Format Options

Our generator supports multiple output formats to match your programming language or framework requirements:

Best Practices for Using UUIDs

When implementing UUIDs in your application, consider these best practices:

Why Choose Our UUID Generator?

Our free online UUID generator offers several advantages over command-line tools or library functions:

Frequently Asked Questions
What is a UUID?

UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. It's represented as 32 hexadecimal digits displayed in 5 groups separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are practically unique and don't require a central authority for generation.

What's the difference between UUID v1 and v4?

UUID v1 is timestamp-based and includes the current time and MAC address, making it sequential and sortable by time. UUID v4 is completely random and is the most commonly used version. V4 is preferred for most use cases as it doesn't leak information about when or where it was generated, while v1 can be useful when you need chronologically sortable identifiers.

How unique are UUIDs? Can they collide?

UUIDs are extremely unique. For UUID v4, the probability of collision is approximately 1 in 2^122 (about 5.3 × 10^36). To put this in perspective, generating 1 billion UUIDs per second for 100 years would still have less than a 50% chance of creating a duplicate. For practical purposes, UUIDs are considered collision-free.

When should I use UUID v5 instead of v4?

Use UUID v5 when you need deterministic UUIDs - meaning the same input (namespace + name) always generates the same UUID. This is useful for generating consistent identifiers from URLs, email addresses, or domain names. Use v4 when you need completely random, unpredictable identifiers for things like database primary keys, session IDs, or temporary tokens.

Can I use UUIDs as database primary keys?

Yes, UUIDs are commonly used as database primary keys. They offer advantages like global uniqueness, no central coordination needed, and security (non-sequential). However, they use more storage (16 bytes vs 4-8 bytes for integers) and can be slower for indexing. Consider using UUID v1 or ordered UUIDs if index performance is critical.

What are NIL and MAX UUIDs used for?

NIL UUID (00000000-0000-0000-0000-000000000000) represents a null or empty UUID value, similar to null in databases. MAX UUID (ffffffff-ffff-ffff-ffff-ffffffffffff) represents the maximum possible UUID value. Both are special-purpose UUIDs used in algorithms, database schemas, or as sentinel values in data structures.

Is it safe to expose UUIDs publicly?

Yes, UUID v4 is safe to expose publicly as it's randomly generated and reveals no information about your system. However, UUID v1 contains timestamp and MAC address information which could leak details about when and where it was created. For public-facing identifiers, use UUID v4 or consider adding additional security layers if using v1.

Can I generate bulk UUIDs offline?

Yes! Our UUID generator works entirely in your browser using JavaScript's crypto API. You can generate up to 1000 UUIDs at once, completely offline, without any server communication. This ensures privacy and allows unlimited generation without rate limits or internet connectivity requirements.

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