UUID Generator - Generate UUID v4 & v7 Online Free

How to Use the UUID Generator

1. Select UUID version — choose between UUID v4 (completely random) or UUID v7 (time-ordered with random component). v4 is the most commonly used for general purposes, while v7 is better for database indexing.
2. Choose quantity — set how many UUIDs to generate, from a single UUID up to 100 at once using the slider or manual input.
3. Toggle options — enable or disable uppercase hex characters. Uppercase is common for display, lowercase is typical in code.
4. Generate — click the Generate button to produce your UUIDs. They appear in a scrollable list format.
5. Copy UUIDs — click the copy icon next to any individual UUID to copy it, or use “Copy All” to copy the entire list at once, one per line.
6. Regenerate — generate a fresh batch anytime with the same settings for new identifiers.

Features

• UUID v4 — cryptographically secure random UUIDs generated using your browser’s crypto API
• UUID v7 — time-ordered UUIDs with millisecond timestamp prefix, ideal for database primary keys
• Bulk generation — generate 1 to 100 UUIDs in a single click
• Copy individual — click any UUID to copy it to your clipboard
• Copy all — copies every generated UUID at once, separated by newlines
• Uppercase toggle — switch uppercase or lowercase hex representation
• No duplicates — each UUID is independently generated, with astronomically low collision probability

Use Cases

• Database primary keys — UUID v7 is time-ordered, reducing B-tree index fragmentation compared to random UUID v4
• API resource identifiers — generate unique IDs for users, orders, products, or any API resource
• Distributed systems — create IDs across multiple servers without coordination, ensuring global uniqueness
• Testing and development — populate test databases, generate mock data, and create sample API responses with realistic IDs
• Session tokens — generate unique session or request identifiers for web applications

FAQ

What’s the difference between UUID v4 and v7?

UUID v4 is entirely random (122 bits of randomness). UUID v7 combines a Unix timestamp in milliseconds (48 bits) with random data (74 bits), making them sortable by creation time — similar to auto-increment IDs but globally unique. v7 is recommended for database primary keys because new values insert sequentially rather than randomly across the index.

Are these UUIDs truly unique?

The probability of a collision is extremely low — roughly 1 in 2^122 for v4 and 1 in 2^74 for v7. In practice, both versions are safe for any application. The browser’s crypto.getRandomValues() provides cryptographically strong randomness.

Are UUIDs generated on the server or in my browser?

All UUIDs are generated entirely in your browser using the Web Crypto API. No data is sent to any server. The generation is private and works offline.

What format do UUIDs use?

Standard 8-4-4-4-12 format: 32 hexadecimal characters with four hyphens, totaling 36 characters (e.g., 550e8400-e29b-41d4-a716-446655440000). You can toggle between lowercase and uppercase.

Can I generate more than 100 at once?

The interface limits bulk generation to 100 for performance and usability. For more, simply generate in batches and combine the results.

Tips

• Use UUID v7 for database primary keys in PostgreSQL, MySQL, and other databases — the time-ordered nature reduces index page splits by ~80% compared to random UUID v4
• For API public IDs (like order numbers), consider using the uppercase option for better readability in URLs and confirmation emails
• When testing, generate 10-20 UUIDs at once and paste them directly into your test fixtures or seed data scripts