UUID Generator — Free Online Tool

What Is UUID Generator?

A free online UUID v4 generator. Create universally unique identifiers using crypto.randomUUID(). Generate single or batch UUIDs (up to 50 at once), toggle hyphens and case, and copy any result. All generation happens locally in your browser.

Universally Unique Identifiers (UUIDs) are essential for modern software development. They serve as database primary keys, session identifiers, distributed system identifiers, and API resource IDs — anywhere you need a unique value that does not require a central authority to coordinate. UUID Generator produces RFC 4122 version 4 UUIDs using your browser's cryptographic random number generator, ensuring every ID is truly unique and unpredictable.

The tool generates UUIDs in the standard 8-4-4-4-12 hexadecimal format (e.g., 550e8400-e29b-41d4-a716-446655440000). Batch generation creates 1, 5, 10, or 50 UUIDs at once — useful for pre-generating identifiers for a new database migration or assigning IDs to resources in batch. Each UUID in the batch is independently random, so there is no sequential pattern that could be guessed.

Customization options cover the most common format variations. Toggle hyphens off to produce a compact 32-character hex string without separators, which is commonly used in file naming or when UUIDs are stored without formatting. Toggle between lowercase and uppercase — some systems prefer uppercase hex representation, while others standardize on lowercase. Each UUID in the batch updates to reflect the current formatting choices.

The generation uses crypto.randomUUID() where available, falling back to a cryptographically secure random implementation using the Web Crypto API. This means the UUIDs are suitable for security-sensitive applications like authentication tokens, password reset links, and session management — not just for test data. No two generated UUIDs will ever be the same, and the random nature makes them unpredictable.

Real-World Use Cases for UUID Generator

Pre-generating Database Primary Keys for Migration

You are migrating user data from a legacy system to a new database that uses UUID primary keys. Generate 50 UUIDs at once in lowercase with hyphens. Map each UUID to a user record during the import process. The batch generation saves time compared to generating IDs one at a time during the migration script.

Creating Unique Session Tokens for a Web Application

A new web app needs session tokens that are unpredictable and unique. Generate individual UUIDs as each user logs in. The cryptographic randomness ensures that session tokens cannot be guessed or enumerated, protecting against session hijacking attacks.

Generating Identifiers for Distributed System Resources

A microservices architecture needs unique resource IDs across multiple independent services that cannot coordinate with a central database. Each service generates UUIDs independently — the random nature guarantees no collisions. Toggle hyphens off for a compact 32-character format that works well in REST API URLs.

Why Use UUID Generator?

Generates RFC 4122 v4 compliant UUIDs
Batch generation: 1, 5, 10, or 50 at once
Toggle hyphens and uppercase/lowercase
Uses crypto.randomUUID() for secure randomness

How to Use UUID Generator — Step by Step

Choose how many UUIDs to generate (1, 5, 10, or 50).

Toggle hyphens on/off and case (lower/upper).

Click Generate for a fresh batch.

Click copy next to any UUID to copy it.

Who Is UUID Generator Best For?

database keys
session IDs
distributed systems
test data

Pro Tips for UUID Generator

1Use lowercase UUIDs by convention — most systems (databases, file systems, URLs) standardize on lowercase hex. Stay consistent rather than mixing cases.
2Keep hyphens enabled for human-readable UUIDs in logs, API responses, and debugging output. Remove hyphens only when storing in databases or using in file paths where the dash might cause issues.
3Generate a batch of 50 UUIDs and store them in a pool for systems that need IDs synchronously. Pull from the pool rather than generating on demand to reduce latency in time-sensitive code paths.
4Version 4 UUIDs are random, not timestamp-based. If you need time-ordered UUIDs for database index performance, consider UUID v7 instead — but v4 is the most universally supported standard across all platforms.

UUID Generator — Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier represented as a 36-character string (32 hex digits + 4 hyphens). Version 4 UUIDs use random numbers, making collisions extremely unlikely.

Are these UUIDs safe for production use?

Yes. The tool uses the browser's built-in crypto.randomUUID() API, which provides cryptographically secure random UUIDs suitable for production use as database keys and identifiers.

Can I use these tools with sensitive/proprietary data?

Absolutely. All processing runs locally in your browser with zero server uploads. This makes these tools safe for proprietary code, internal API keys, and confidential data.

Do these tools work offline?

Yes, once the page has loaded, most developer tools continue functioning without an internet connection. This makes them ideal for air-gapped environments or travel.

What browsers are supported?

All modern browsers are supported: Chrome, Firefox, Safari, and Edge. Internet Explorer is not supported. The tools leverage modern JavaScript APIs like Web Crypto, TextEncoder, and BigInt.

Ready to Use UUID Generator?

Free online tool — works in your browser, no sign-up required. Start using it right now.

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