圖片壓縮線上工具 - 免費批次壓縮 JPG/PNG/WebP Image Compressor — Free Online Batch Compression

JPG 和 WebP 是有損壓縮，壓縮後畫質確實會略降，但在品質 75 以上，人眼通常看不出明顯差異。PNG 壓縮則是無損的，只縮小檔案大小，不影響畫質。 JPG and WebP use lossy compression, so quality does drop slightly. However, above quality 75, the difference is usually invisible to the naked eye. PNG compression is lossless — it only reduces file size without any quality loss.

預設的 80 對大多數用途都很合適，網頁圖片、社群媒體發文等場合都足夠。如果是需要印刷或高細節呈現的圖片，可以拉到 90 以上。低於 60 才會開始出現明顯的色塊或模糊。 The default of 80 is suitable for most uses — web images, social media, etc. For print or high-detail work, push it to 90+. Below 60 is where noticeable artifacts start to appear.

有些圖片本身已經是高度壓縮過的狀態，再壓一次反而可能讓工具為了保留品質而產生更大的檔案。這種情況下直接使用原始檔案就好，結果卡片也會標示「原檔已最佳化」讓你知道。 Some images are already heavily compressed. Re-compressing them can result in a larger file as the encoder works to preserve quality. In this case the result card shows "Already Optimized" and the original file is returned.

完全不會。所有壓縮都在你的瀏覽器裡完成，圖片從來不會離開你的裝置。就算網路斷線，這個工具也能正常運作。 Not at all. All compression runs inside your browser. Your images never leave your device, even when offline.

因為所有運算都在你的瀏覽器裡發生，伺服器不需要做任何處理，所以幾乎沒有運算成本。工具本身就是這樣能免費提供的原因，不需要你登入或付費。 Because all processing happens in your browser — the server does nothing. With virtually no compute costs, we can offer the tool completely free, no login or payment required.