UUID Generator

Generate universally unique identifiers (UUIDs) in standard formats. Create version 1, 4, or 5 UUIDs for database keys and identifiers.

100% client-side No signup Free forever

Generate Multiple UUIDs

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About UUIDs

A UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across both space and time.

UUID Versions

VersionDescription
Version 1Based on timestamp and MAC address
Version 4Randomly generated (most commonly used)

UUID Structure

xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

  • M indicates the UUID version
  • N indicates the UUID variant
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How to Use UUID Generator

How to Use the UUID Generator

  1. Select UUID version: Choose v1 (time-based), v4 (random), or v5 (name-based). V4 is recommended for most uses.
  2. Set quantity: Choose how many UUIDs to generate (1-100).
  3. Format options: Select with hyphens, without hyphens, or uppercase.
  4. For v5: Enter a namespace and name to generate deterministic UUIDs.
  5. Generate: Click Generate to create your UUIDs.
  6. Copy: Copy individual UUIDs or all at once.

UUID Probability of Collision

The probability of generating two identical v4 UUIDs is astronomically small. You would need to generate 2.71×10^18 UUIDs to have a 50% chance of one collision. For practical purposes, they are unique.

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Features

  • UUID v1, v4, and v5 generation
  • Bulk UUID generation (up to 100)
  • With or without hyphens format
  • Uppercase or lowercase option
  • Namespace and name input for v5
  • One-click copy single UUID
  • Copy all UUIDs at once
  • Guaranteed uniqueness
  • RFC 4122 compliant
  • No registration required
  • Works offline
  • Mobile-friendly interface
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About UUID Generator

UUIDs (Universally Unique Identifiers) provide globally unique identification without central coordination. Whether you're designing databases, building APIs, or tracking distributed events, UUIDs ensure every identifier is unique across space and time.

UUID Versions Explained

Different versions serve different needs:

  • Version 1: Based on timestamp and MAC address, sortable by creation time
  • Version 4: Purely random, most commonly used, highest privacy
  • Version 5: Generated from namespace and name using SHA-1 hash

When to Use Each Version

Version 4 (random): Default choice for most applications. No information leakage, uniform distribution. Version 1 (time-based): When chronological ordering matters, like event logs. Version 5 (name-based): When you need deterministic IDs from consistent inputs.

Database Primary Keys

UUIDs as primary keys avoid bottlenecks of sequential integers: no need for central ID generation, safe for distributed systems, no information leakage about record count. Tradeoffs include larger storage size and less cache-friendly access patterns.

UUID Format

Standard format: 8-4-4-4-12 hexadecimal characters (e.g., 550e8400-e29b-41d4-a716-446655440000). The 128-bit value provides 2^122 possible UUIDs—enough that collisions are statistically impossible in practical applications.

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Frequently Asked Questions

What is a UUID and why would I need one?
A UUID (Universally Unique Identifier) is a 128-bit identifier guaranteed to be unique across space and time. UUIDs are used in databases, distributed systems, session tokens, and anywhere you need unique identifiers without central coordination. The probability of generating duplicate UUIDs is negligible.
What is the difference between UUID versions?
UUID v1 uses timestamp and MAC address (can leak device info). UUID v4 is completely random (most common, recommended for most uses). UUID v5 creates deterministic UUIDs from a namespace and name using SHA-1. UUID v7 is timestamp-ordered random (newest, ideal for databases). We support all versions.
Which UUID version should I use?
For most applications, UUID v4 (random) is recommended - it's simple and widely supported. For database primary keys where you want time-ordering, use UUID v7. For deterministic IDs (same input = same UUID), use UUID v5. Avoid v1 unless you specifically need timestamp extraction.
Are UUIDs secure for use as tokens or secrets?
UUID v4 uses cryptographically secure random generation and is safe for session tokens and identifiers. However, UUIDs are not passwords - they're 122 bits of randomness formatted as text. For secrets requiring specific formats or higher entropy, use a dedicated secret generator.
Can two UUIDs ever be the same?
Theoretically yes, but practically no. With UUID v4, the probability of collision is 50% only after generating 2.71×10^18 UUIDs. You'd need to generate 1 billion UUIDs per second for 85 years to have a 50% chance of one duplicate. For all practical purposes, they're unique.
How do I generate multiple UUIDs at once?
Our generator lets you create up to 100 UUIDs at once with one click. You can choose the version, format (with or without hyphens, uppercase or lowercase), and copy all generated UUIDs to your clipboard. This is useful for seeding databases or creating batch identifiers.