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🔁 UUID Generator

Free Online UUID Generator (UUID v4)

Generate cryptographically random UUID v4 identifiers instantly — bulk generate up to 50 at once, uppercase or lowercase, with or without hyphens. 100% in your browser, nothing uploaded.

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What Is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit value, usually written as 32 hex digits split into five groups (e.g. 3fa85f64-5717-4562-b3fc-2c963f66afa6). It's designed so that any two UUIDs generated independently — on different servers, at different times, by different people — are effectively guaranteed never to collide. That makes UUIDs the standard choice for database primary keys, API request IDs, session tokens, and file names in distributed systems where a central auto-increment counter isn't practical.

Why UUID v4?

UUID has several versions; v4 is the one you want by default. It's generated from 122 bits of randomness (the other 6 bits mark it as version 4), using crypto.getRandomValues() under the hood — the same cryptographically secure random number source used by production systems. Unlike v1, it doesn't leak your machine's MAC address or the exact creation timestamp, which makes it the safer, more private choice for public-facing IDs.

UUID 生成器

这是一个免费的在线 UUID v4 生成器，可批量生成最多 50 个随机 UUID，支持大写和无连字符格式，一键复制。所有生成过程均在浏览器本地完成，使用 Web Crypto API 保证随机性强度，适合用作数据库主键、API 请求 ID 等生产环境用途。

Frequently Asked Questions

What is a UUID and why would I need one?▼
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information — database rows, API requests, sessions, files — without needing a central authority to coordinate IDs. Developers use UUIDs instead of auto-incrementing integers when IDs need to be generated independently across multiple servers or clients without collisions.
What is a UUID v4 specifically?▼
UUID v4 is the most common UUID version — it's generated using random or pseudo-random numbers rather than being derived from a timestamp or hardware address (like v1) or a name (like v3/v5). This tool uses crypto.getRandomValues() / crypto.randomUUID(), which provides cryptographically strong randomness suitable for production use.
Is this UUID generator safe to use for production database keys?▼
Yes. The UUIDs are generated entirely in your browser using the Web Crypto API (crypto.randomUUID()), the same cryptographically secure random number generator used by Node.js, browsers, and most programming language standard libraries. Nothing is sent to a server, and the randomness quality is production-grade.
Can I generate UUIDs in uppercase or without hyphens?▼
Yes. Toggle "Uppercase" to get IDs like 3FA85F64-5717-4562-B3FC-2C963F66AFA6, or toggle "No hyphens" to get a compact 32-character string like 3fa85f6457174562b3fc2c963f66afa6 — useful for systems that store UUIDs as fixed-length strings without separators.
What's the difference between UUID v4 and UUID v1 or v7?▼
UUID v1 encodes the creation timestamp and the generating machine's MAC address, which can leak information and isn't ideal for privacy. UUID v7 (newer) is timestamp-ordered, which makes it more efficient as a database primary key because it sorts naturally and avoids index fragmentation. UUID v4 is purely random — the safest default when you don't need timestamp ordering.
Is my data sent to a server when I use this tool?▼
No. Every UUID is generated entirely inside your browser using JavaScript's Web Crypto API. Nothing is uploaded, logged, or transmitted. You can disconnect from the internet after the page loads and the generator will keep working.

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Guides

UUID Versions Explained: v1 vs v4 vs v7 → How to Generate UUIDs in JS, Python & SQL →