Generate UUID v4 (cryptographically random) and modern UUID v7 (timestamp-ordered, RFC 9562) identifiers in bulk — up to 100 at a time — with custom uppercase and hyphen formatting.
UUID v4 provides 122 bits of pure randomness, ideal for secure stateless tokens. UUID v7 combines a 48-bit millisecond Unix timestamp with 74 random bits, giving monotonic time ordering that drastically improves database B-tree index performance and cache locality.
Frequently asked questions
What is the difference between UUID v4 and UUID v7?
UUID v4 is completely random. UUID v7 encodes a 48-bit millisecond timestamp in the prefix, so UUIDs sort chronologically by creation time.
Why use UUID v7 for database primary keys?
Pure random UUIDs cause page fragmentation in B-trees (random disk writes). UUID v7 is sequential, meaning new inserts append near the end of index leaves, boosting throughput.
Can two generated UUIDs collide?
The chance is astronomically small — you would need billions generated per millisecond to observe collisions.
中文说明
批量生成随机 UUID v4 以及现代时间有序的 UUID v7（RFC 9562 标准），支持自定义大小写与连字符格式，单次最高可生成 100 个。
UUID v4 提供 122 位纯密码学随机性，适合无状态安全令牌；UUID v7 将 48 位 Unix 毫秒时间戳与 74 位随机数结合，具有天然的时间单调递增性，可大幅提升 PostgreSQL、MySQL 等数据库的 B 树索引性能与写入局部性。
常见问题
UUID v4 和 UUID v7 有什么区别？
UUID v4 完全随机；UUID v7 前缀包含 48 位毫秒时间戳，生成的 ID 天然按创建时间排序。
为什么数据库主键推荐 UUID v7？
纯随机的 UUID v4 会导致 B+ 树索引严重碎片化；UUID v7 具有时间局部性，新记录追加在索引末尾，显著降低 I/O 压力。
两个 UUID 可能发生碰撞重复吗？
概率微乎其微——即使在同一毫秒内也拥有 74 位的随机熵，需要每毫秒生成数十亿个才可能碰撞。