Free Online Tool

UUID / GUID Generator

Generate universally unique identifiers instantly. Support for UUID v1, v4, v7, ULID, and Nano ID with bulk generation up to 1000, validation, parsing, and multiple output formats. Free, browser-based, no signup.

Developer Tool Browser-based
Cryptographically Secure Instant Generation Bulk Support — up to 1000
Local browser generation
550e8400-e29b-41d4-a716-446655440000
Enter a number between 1 and 1000.
Ready — identifiers are generated locally using the Web Crypto API.
Click “Generate UUIDs” to create unique identifiers
Session only — generated values are not uploaded or stored on our servers.

UUID Version Comparison

Version Size Sortable Time-Based Randomness Best For
UUID v1 128 bits ✓ Partial ✓ Yes Low (clock + node) Legacy distributed systems
UUID v4 128 bits ✗ No ✗ No High (122 bits) General purpose
UUID v7 128 bits ✓ Yes ✓ Unix ms Medium (74 bits) Database primary keys
ULID 128 bits ✓ Yes ✓ Unix ms Medium (80 bits) URL-safe, sortable IDs
Nano ID Configurable ✗ No ✗ No High Short URL-friendly IDs

Powerful UUID Generation Features

Everything you need to generate, validate, and export unique identifiers for any project.

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Cryptographically Secure

Uses the Web Crypto API (crypto.getRandomValues) for secure random generation with high entropy.

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Bulk Generation

Generate up to 1000 identifiers at once for database seeding, test data and batch processing.

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Multiple Versions

Support for UUID v1, v4, v7, ULID and Nano ID — covering general-purpose and database-optimized use cases.

✅

Validation & Parsing

Validate UUIDs and inspect version, variant, timestamps and node information where available.

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Multiple Formats

Output standard, uppercase, no hyphens, braces or URN format to match your codebase requirements.

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Export Options

Copy identifiers to your clipboard or download bulk output as a plain text file for scripts and fixtures.

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Browser Based

No signup or backend is required. Generation happens directly in your browser.

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Privacy First

Generated values stay in the current browser session and are never sent to a generation service.

UUID Structure Explained

550e8400-e29b-41d4-a716-446655440000
550e8400time_low32 bits
e29btime_mid16 bits
4version4 bits
1d4time_hi12 bits
avariant2–3 bits
716clock_seq13–14 bits

A UUID is 128 bits (16 bytes) represented as 32 hexadecimal digits, commonly displayed in five groups separated by hyphens in the form 8-4-4-4-12. The version field identifies the UUID type, while the variant bits identify the UUID layout.

UUID & GUID Guide — Everything Developers Need to Know

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier) in Microsoft ecosystems, is a 128-bit identifier. UUIDs are designed to be globally unique without requiring a central registration authority, making them useful for distributed systems, databases and APIs.

UUID Formats Reference

Format Example
Standard 550e8400-e29b-41d4-a716-446655440000
Uppercase 550E8400-E29B-41D4-A716-446655440000
No Hyphens 550e8400e29b41d4a716446655440000
Braces {550e8400-e29b-41d4-a716-446655440000}
URN urn:uuid:550e8400-e29b-41d4-a716-446655440000

UUID Use Cases in Development

UUID v4 vs v7 — Which to Choose?

Feature UUID v4 UUID v7
Randomness 122 bits 74 bits
Time-ordered No Yes (millisecond precision)
DB index performance Less locality Excellent locality
Privacy No timestamp Timestamp exposed
Best for General use New database primary keys

UUID Collision Probability

💡 Pro Tips for UUID Usage

  1. Use UUID v7 for new database projects when time ordering and index locality are useful.
  2. Store as BINARY(16) in MySQL/MariaDB when using UUIDs as database keys to reduce storage versus VARCHAR(36).
  3. Use ULID for sortable identifiers when its 26-character representation fits your application.
  4. Use Nano ID for short public-facing IDs where a compact URL-friendly identifier is preferred.
  5. Validate before storing UUIDs received from external sources.
  6. Bulk generate test data to seed development and staging databases.
  7. Consider privacy before using UUID v1; classic v1 UUIDs can expose node information and timing data. This page uses a randomized node instead of a real MAC address.

Frequently Asked Questions

Common questions about UUIDs, GUIDs, and unique identifier generation.

A UUID is a 128-bit identifier designed to be unique across space and time without a central registration authority. Common uses include database keys, session identifiers, transaction IDs, file identifiers and API request tracking.

UUID and GUID generally describe the same 128-bit identifier concept. “GUID” is the terminology commonly used by Microsoft technologies, while “UUID” is the broader standards terminology.

UUID v1 is time-based and includes node/clock information, while UUID v4 is generated from random bits. v4 is a common general-purpose choice when you do not need ordering.

UUID v7 combines a Unix millisecond timestamp with random data. Its time-ordered nature can improve locality for database indexes compared with purely random UUID v4 values, while retaining a large random component.

ULID is a 128-bit identifier represented as 26 Crockford Base32 characters. It contains a millisecond timestamp followed by randomness, making it compact and naturally sortable by creation time.

Nano ID is a compact, URL-friendly identifier format. This implementation generates a 21-character ID from a 64-character alphabet using browser cryptographic randomness.

No finite identifier space can provide an absolute mathematical guarantee, but a correctly generated UUID v4 has such a large random space that collisions are extraordinarily unlikely for normal applications.

Use UUID v4 for a straightforward random identifier. Consider UUID v7 when time ordering and database index locality are important. ULID is useful when a sortable, compact text representation is preferred.

UUIDs can serve as primary keys, public resource identifiers, correlation IDs and replication-friendly identifiers. Choose the representation and indexing strategy based on the database and workload.

The generator uses the browser Web Crypto API for random values and does not send generated IDs to a server. Always test the identifier format and application-level requirements before adopting any generator in production.

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Privacy & security notice

This UUID / GUID generator runs entirely in your web browser. Random identifiers are produced with the Web Crypto API where available. Generated values are not transmitted to a generation service, and the recent history exists only in the current page session.