UUID Generator は何をしますか？
UUID Generator はブラウザ上で結果を生成するツールで、結果と制限を明確に示します。 検証済みの機能： UUID v4, UUID v7, Bulk generation up to 100, Version and variant inspection.
Choose v4 for privacy or v7 for locality
Use UUID v4 when identifiers should not expose creation time. Use UUID v7 when approximate time ordering improves database or event-log locality.
使い方
- Choose UUID v4 for random identifiers or UUID v7 for roughly chronological identifiers.
- Choose a count from 1 to 100 and optional uppercase display.
- Generate and copy the newline-separated values.
実際の入出力例
Inspect a version-4 identifier
入力
550e8400-e29b-41d4-a716-446655440000出力
Version: 4
Variant: RFC 4122/9562The version nibble is 4 and the variant bits match the standard UUID layout.
一般的なエラーと対処
| 症状 | 原因 | 対処 |
|---|---|---|
| Validation rejects a UUID. | The hyphens, hexadecimal length, version, or variant bits are invalid. | Use the canonical 8-4-4-4-12 hexadecimal layout and a supported version. |
| UUID v7 order is not exact. | Values share a millisecond or were created on clocks with different time state. | Treat v7 as roughly time ordered and keep a separate authoritative timestamp when exact order matters. |
A UUID is not a secret
このツール固有の制限： Collisions are theoretically possible but extremely unlikely with correctly generated UUID v4 values. UUIDs identify records; they do not prove authorization or provide secrecy.
標準と実装の参考資料
- RFC 9562 — UUIDs (opens in a new tab)Defines UUID versions 4 and 7, variants, and layout.
UUID Generator — FAQ
Are UUID v4 values cryptographically random?
Yes. The tool uses crypto.randomUUID or crypto.getRandomValues and sets the RFC version and variant bits.
What is different about UUID v7?
UUID v7 starts with a 48-bit Unix-millisecond timestamp and keeps random bits.
Does uppercase change the value?
No. UUID hexadecimal text is case-insensitive.
更新内容
実質的な更新： UUID Generator: Added UUID v4 and v7 generation, up to 100 values, uppercase display, copy, and version and variant inspection.