塗黑 PDF 中的機密資訊
在想要移除的內容上繪製方框——是真正永久移除，而不只是遮蓋起來。
運作方式
1. 上傳您的 PDF。2. 在任何頁面上，於想要塗黑的每個部分繪製方框。3. 下載——這些區域會被永久移除，而不只是被遮蓋。
內容是真的被移除，還是只是蓋上黑色方框？
真的會被移除。經過塗黑的頁面，會在轉換為平面圖片前，先將標記區域塗成黑色再進行平面化——因此底下不會留下任何可複製、可選取或可還原的文字或隱藏資料。這和只在上方畫一個方框的工具不同，那種方式底下的文字仍可能被人刪除方框後複製出來看到。
這會影響我沒有標記的頁面嗎？
不會——只有至少含一個塗黑方框的頁面才會被轉換成圖片。您沒有動過的頁面，會保留原本的文字、畫質與檔案大小。
塗黑後的頁面文字還能被選取或搜尋嗎？
不能，這是刻意的——只要頁面上有任何內容被塗黑，整頁就會變成一張平面化的圖片，這正是確保隱藏內容無法被還原的關鍵。
Can I undo a redaction after I've downloaded the file?
No. Once you download, the redacted pages are baked into a new PDF and there's no getting the original content back. You can still remove or adjust a box before you download, though — nothing is final until you export.
Can I search for a word and redact every instance of it automatically?
No — this tool only redacts what you draw a box over. If a name or number appears five times in your PDF, you have to box out all five yourself. There's no find-and-redact-all feature.
Will my file get bigger after redacting?
Usually, yes. Any page with a redaction on it gets turned into a compressed image instead of live text, so even redacting one line can make that page's file size bigger than it was originally — that's the tradeoff for making the content truly unrecoverable.
Does redacting also strip hidden metadata, like the author's name or document title?
Yes, as a side effect. The output is built as a brand-new PDF rather than a patched copy of your original, so metadata like the author and title from your source file doesn't carry over.