CSS/JS圧縮ツール
CSSとJavaScriptコードの圧縮と整形
使い方
テキストを貼り付けまたは入力
テキスト、コード、またはデータを入力エリアに入力します。
オプションを選択
適用する変換やフォーマットを選択します。
結果をコピー
ワンクリックで出力をクリップボードにコピーします。
このツールを使う理由
完全無料
隠れたコストもプレミアムプランもありません — すべての機能が無料です。
インストール不要
すべてブラウザで実行されます。ソフトウェアのダウンロードやインストールは不要です。
プライベート＆安全
データはデバイスの外に出ることはありません。サーバーにアップロードされることはありません。
モバイル対応
完全レスポンシブ対応 — スマートフォン、タブレット、デスクトップで利用できます。
CSS and JavaScript Minification for Web Performance
Key Takeaways
- Minification removes whitespace, comments, and unnecessary characters to reduce file sizes by 20–60% on average.
- Smaller CSS and JavaScript files mean faster page loads, especially on mobile networks with limited bandwidth.
- All minification runs in your browser — your source code stays completely private.
Every kilobyte matters for web performance. CSS and JavaScript minification is a fundamental optimization that strips unnecessary characters from source code without changing functionality. While build tools like Webpack and Vite handle this automatically in production pipelines, a quick online minifier is invaluable for one-off optimizations, email templates, and embedded scripts.
Minification typically reduces CSS file sizes by 20–40% and JavaScript by 30–60%.
Size Reduction
Common Use Cases
Email Template Optimization
Minify inline CSS in HTML email templates to stay under email client size limits and improve rendering speed.
Third-Party Script Embedding
Minify JavaScript snippets before embedding them as inline scripts in CMS platforms or widget integrations.
Performance Auditing
Quickly check how much size reduction minification would achieve for files flagged in Lighthouse performance audits.
CDN Payload Optimization
Minify static assets before uploading to CDNs that do not offer automatic minification at the edge.
Pro Tips
Always keep your original unminified source files in version control — minified code should only be used in production.
Combine minification with gzip or Brotli compression for maximum file size reduction — they complement each other well.
Test minified code thoroughly, as aggressive minification can occasionally break CSS specificity or JavaScript variable scoping.
Use source maps in development to debug minified code by mapping it back to the original readable source.
All CSS and JavaScript minification is performed entirely in your browser. Your source code is never uploaded to any server, ensuring your proprietary code and business logic remain completely private.