🆔 UUID v4 在线生成器 — 免费安全
Generate cryptographically secure UUID v4 and ULID identifiers. Bulk generate up to 20 at once. No signup, no server — runs in your browser.
Click Generate for an instant cryptographically secure UUID v4, or switch to ULID for a sortable identifier. Generate 1–20 at once and copy individually or all at once. Everything runs in your browser using the Web Crypto API — no server, no logging.
How to Use
1
Choose type and count
Select UUID v4 or ULID from the type selector, then set the count (1–20).
2
Click Generate
Press Generate to instantly create cryptographically secure identifiers.
3
Copy your IDs
Click the Copy button next to any ID, or use Copy All to copy the entire list.
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects in software. UUID v4 is randomly generated, producing IDs like "550e8400-e29b-41d4-a716-446655440000". The probability of collision is astronomically low.
What is the difference between UUID v4 and other UUID versions?
UUID v1 is based on time and MAC address. UUID v3 and v5 are name-based using MD5/SHA-1 hashes. UUID v4 is fully random and is the most commonly used version for databases and distributed systems.
What is a ULID?
ULID (Universally Unique Lexicographically Sortable Identifier) is an alternative to UUID that is sortable by creation time. It is 26 characters in Crockford Base32. The first 10 characters encode millisecond timestamp, the remaining 16 are random.
Are generated UUIDs truly unique?
UUID v4 uses cryptographic randomness (crypto.getRandomValues). The probability of generating a duplicate UUID is 1 in 5.3×10^36 — effectively zero for all practical purposes.
Is any data sent to a server?
No. UUIDs and ULIDs are generated entirely in your browser using the Web Crypto API. Nothing is sent to any server.
完整指南：UUID/GUID生成器
什么是UUID？
UUID是格式为xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx的128位标识符。UUID v4使用密码学随机数——碰撞概率极低，可生成数十亿个而无重复。
如何使用
- 选择版本：v4（随机）是最常用的。
- 选择批量数量。
- 点击生成并复制UUID。
专业技巧
- 默认使用v4；需要时间排序时使用v7（时间戳优先）。
- PostgreSQL中原生
uuid类型比VARCHAR更高效。 - 公开URL考虑使用更短的ID（nanoid、ULID）。