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UUID Generator

Generate secure UUID v4 identifiers instantly in your browser. No backend, no tracking, no unnecessary complexity.

Generated UUID v4

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Generate UUID v4

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What is a UUID?

A UUID, short for Universally Unique Identifier, is a standardized 128-bit value used to identify something without relying on one central numbering system. It often looks like this: 550e8400-e29b-41d4-a716-446655440000.

In simple terms, a UUID is a long label that is so unlikely to repeat that many systems can create identifiers independently and still work together safely.

UUID Versions

UUID version comparison table
VersionBased onCommon useNotes
UUID v1Time and nodeLegacy systemsCan expose time and machine-related data.
UUID v3MD5 namespace hashDeterministic IDsSame input creates the same UUID.
UUID v4Random valuesGeneral-purpose IDsSimple and widely supported.
UUID v5SHA-1 namespace hashDeterministic IDsPreferred over v3 for namespace hashing.
UUID v6Reordered v1 timeSortable IDsImproves database ordering over v1.
UUID v7Unix timestamp and random dataModern sortable IDsUseful for logs, events, and ordered inserts.

Why use UUIDs?

Advantages

  • Can be generated without a central database.
  • Work well across distributed systems.
  • Reduce predictable sequential IDs in public URLs.
  • Supported by many languages and databases.

Disadvantages

  • Larger than integer IDs.
  • Random UUIDs can fragment database indexes.
  • Harder for people to read or type manually.
  • Should not be treated as secret tokens.

UUID Examples

JavaScript

crypto.randomUUID();

Python

import uuid
uuid.uuid4()

Django

id = models.UUIDField(
    primary_key=True,
    default=uuid.uuid4
)

PostgreSQL

SELECT gen_random_uuid();

MySQL

SELECT UUID();

Node.js

import { randomUUID } from 'crypto';
randomUUID();

Java

UUID.randomUUID();

Go

uuid.NewString()

Rust

Uuid::new_v4()

C#

Guid.NewGuid();

Frequently Asked Questions

What is a UUID?

A UUID is a standardized identifier used to label records, objects, files, and events.

Is UUID v4 random?

Yes, UUID v4 uses random values with fixed version and variant bits.

Are UUIDs unique?

They are practically unique when generated with a good random source.

Does this tool store my UUIDs?

No. Everything runs locally in your browser.

Can I generate 1000 UUIDs?

Yes. The quantity field supports 1 through 1000 UUIDs.

What is a GUID?

GUID is a term often used by Microsoft for UUID-style identifiers.

Should I use UUIDs in URLs?

Yes, if you want non-sequential public identifiers, but still enforce permissions.

Are UUIDs secure tokens?

No. Use dedicated secure token generation for passwords, sessions, and secrets.

Which UUID version is best?

UUID v4 is a good default. UUID v7 is often better when sorting by creation time matters.

Can UUIDs collide?

Collisions are possible in theory but extremely unlikely with correct generation.

Why are there hyphens?

Hyphens are part of the common canonical text format and improve readability.

Can I remove UUID hyphens?

Some systems allow it, but the canonical format with hyphens is more portable.

Best Practices

  • Use built-in UUID functions where available.
  • Normalize UUID casing before comparison.
  • Store UUIDs in native database UUID types when supported.
  • Consider UUID v7 for high-write database tables.

Common Mistakes

  • Using UUIDs as a replacement for access control.
  • Generating UUIDs with weak random functions.
  • Mixing uppercase, lowercase, and hyphenless formats without normalization.
  • Ignoring database index behavior for large tables.

Security Considerations

UUID v4 values generated with secure browser crypto are difficult to guess, but they are identifiers, not secrets. Do not use UUIDs alone for password resets, session cookies, API keys, or permission checks.

Browser Compatibility

Modern browsers support the Web Crypto API, and many support crypto.randomUUID(). This generator uses crypto.randomUUID() first and falls back to secure random bytes through crypto.getRandomValues().

Conclusion

UUIDs are a practical way to create unique identifiers for modern applications. UUID v4 is simple, reliable, and widely supported, making it an excellent default for many client-side and server-side workflows.