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UUID ジェネレーター

RFC 4122

RFC 4122 v4 と時間順序の v7 UUID を一括生成。大文字・ハイフンなし形式に対応。

Web Crypto · RFC 4122/9562

ランダム 122 ビット値(RFC 4122)。多くの識別子に最適。

結果

未生成

「UUID を生成」をクリックして作成

About

About UUID Generator

Choose a version and a count, and the generator produces a batch of UUIDs instantly. Version 4 UUIDs are built from 122 random bits, which makes them ideal for general-purpose identifiers. Version 7 UUIDs embed a millisecond timestamp, so they are time-ordered, sortable, and friendlier to database indexes.

Formatting options let you output uppercase values or remove dashes for compact 32-character keys. Copy individual values or the whole batch with one click - nothing leaves your device.

UUIDs are generated with the browser's cryptographically secure random number generator, so collisions are astronomically unlikely and the output is unpredictable.

機能ハイライト

  • RFC 4122 version 4 UUIDs (random)
  • RFC 9562 version 7 UUIDs (time-ordered)
  • Bulk generation up to 100 at once
  • Uppercase and dash-free formatting
  • One-click copy per value or entire batch
  • 100% client-side with Web Crypto randomness
    • FAQ

    UUID Generator FAQ

    Find answers to common questions about generating UUIDs, choosing a version, and formatting output.

    What is the difference between UUID v4 and v7?

    Version 4 UUIDs are entirely random (122 random bits), which makes them unpredictable and ideal for most identifiers. Version 7 UUIDs embed the current millisecond timestamp followed by random bits, so they increase over time and sort naturally - a better fit for database primary keys and log ordering.

    Can two generated UUIDs collide?

    Practically never. Version 4 offers 122 random bits (about 5.3 x 10^36 possibilities), and the browser's CSPRNG is the same source used for TLS keys. Generating billions of UUIDs per second for centuries would still make a collision unlikely.

    Should I use v4 or v7 for my database primary keys?

    For large tables, v7 is usually the better choice because time-ordered values reduce index fragmentation and keep inserts near the end of the index. For client-generated keys where order does not matter, v4 is fine.

    What do the formatting options do?

    Uppercase outputs the UUID in capital letters. Remove dashes strips the hyphens to produce a compact 32-character hexadecimal string, useful for tokens or constrained storage fields.

    Is a GUID the same as a UUID?

    Effectively yes for this tool. GUID is Microsoft's name for UUIDs. This generator follows RFC 4122 and RFC 9562, which are the canonical specifications used across most platforms.

    Is my data sent anywhere?

    No. All UUIDs are generated locally in your browser with Web Crypto. Nothing is transmitted, logged, or stored.