UUID / NanoID ジェネレーター
エンコードと暗号化 · 無料オンラインツール
UUID v4 と NanoID を一括生成。
Click "Generate" to create UUID v4 identifiers...
UUID v4
crypto.randomUUID() で生成 — ハイフン付き 36 文字、RFC 4122 準拠、暗号学的にランダム。
NanoID
URL セーフなアルファベット ( A-Za-z0-9_-) から 21 文字、コンパクトで衝突耐性が高く短縮リンクや ID に最適。
安全な乱数
両方のジェネレータは予測不可能な CSPRNG グレードのエントロピーに Web Crypto API ( getRandomValues) を使用します。
UUID / NanoID ジェネレーターの使い方
- 1Enter or paste your data into the input field.
- 2Select the desired encoding, hashing, or encryption options.
- 3Click the action button to process your data.
- 4Copy the result from the output field.
機能と特徴
- ✓完全無料 — 登録不要、サブスクリプションなし、広告なし
- ✓ブラウザ上で完全に動作 — データは端末から送信されません
- ✓高速・軽量 — 即座に結果を表示
- ✓クロスプラットフォーム — デスクトップ・タブレット・モバイル対応
UUID / NanoID ジェネレーターとは？
UUID (Universally Unique Identifier), defined by RFC 4122 and updated by RFC 9562, is a 128-bit identifier represented as 8-4-4-4-12 hexadecimal string (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are designed to be globally unique without central coordination, making them ideal for distributed systems.
UUID / NanoID ジェネレーターの仕組み
UUID v4 uses cryptographically secure random numbers for 122 bits (6 bits are version/variant markers). UUID v7 (RFC 9562) combines a Unix millisecond timestamp with random bits, producing time-sortable IDs that improve database index locality. Collision probability for v4 is negligible (~10^-37).
よくある使用例
- ✓Database primary keys — avoid auto-increment ID conflicts in sharded DBs
- ✓Distributed systems — unique IDs without central coordinator
- ✓Message tracking — correlation IDs in microservices
- ✓Session tokens — unique session identifiers
UUID v4 vs UUID v7
v4 is fully random; v7 is time-sortable (RFC 9562). v7 IDs generated close in time share prefixes, improving B-tree index locality and database write performance. v4 creates random index entries causing fragmentation. For new systems requiring database storage, prefer v7; for pure randomness (e.g., tokens), v4 is fine.
セキュリティとプライバシー
This tool uses the Web Crypto API (crypto.getRandomValues) for cryptographically secure random numbers. UUIDs are identifiers, NOT security tokens — they are predictable in structure. For security tokens, use a dedicated token generator with sufficient entropy.
技術的な詳細
Standard: RFC 4122 (original), RFC 9562 (2024 update with v6/v7/v8). Format: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx (M=version, N=variant). v1: timestamp + MAC address. v3: MD5 hash of name. v4: random (122 bits). v5: SHA-1 hash of name. v6: reordered v1 (time-sortable). v7: Unix ms timestamp + random. v8: custom. Version bits: bits 48-51 of the UUID.
よくある質問
Can UUIDs collide?
Theoretically yes, practically no. v4 has 2^122 possible values — the probability of collision among 10^18 UUIDs is ~10^-15. You are more likely to be struck by a meteor.
Should I use UUID as a primary key?
Yes for distributed systems. Prefer v7 for better index locality. v4 random UUIDs can cause index fragmentation at scale. Alternatively use snowflake IDs or ULID.
What is the difference between UUID and GUID?
GUID is Microsoft's implementation of UUID (RFC 4122). They are functionally identical. GUID typically uses mixed case; UUID standard is lowercase.