為 PDF 加上數位簽章
加入真正的加密簽章，證明是誰簽署的、且內容自簽署後未被更改——不只是簽名的圖片。
運作方式
1. 上傳您的 PDF。2. 當場建立免費簽章，或上傳您已擁有的憑證（.pfx/.p12）。3. 下載——PDF 現在帶有任何 PDF 閱讀器都能驗證的真正數位簽章。
這和「填寫並簽署」有什麼不同？
「填寫並簽署」只是把您的簽名圖片蓋在頁面上——看起來沒問題，但沒有什麼能阻止別人在事後修改檔案而不被發現。這個工具會嵌入真正的加密簽章：任何 PDF 閱讀器都能驗證它，一旦簽署後有任何一個位元組被更動，就會被標示出來。
這兩種簽署方式有什麼差別？
「建立免費簽章」會當場產生一張與您輸入的姓名和電子郵件綁定的憑證——它能證明檔案在簽署後未被更動，但由於沒有憑證機構為您的身分背書，PDF 閱讀器在有人選擇信任之前，會將它顯示為未驗證。「使用我的憑證」則讓您用已擁有的 .pfx/.p12 檔案簽署（例如用於報稅、GST 或標案申報的印度 DSC 數位憑證）——由於是受認可的機構所核發，信任該機構的閱讀器會自動將簽章顯示為已驗證。
自簽憑證具有法律效力嗎？
這取決於您所在的國家與使用情境——就加密技術而言，它能證明檔案完整性（內容未被更動）以及簽署者身分，但不具備由合法憑證機構核發簽章所擁有的相同法律效力。若要用於合約或申報文件，請先確認您所在地區的具體規定。
我的憑證密碼或私密金鑰會被傳送到任何地方嗎？
不會——一切都在您的瀏覽器中完成。您的憑證、密碼與私密金鑰絕不會離開您的裝置。
Which laws actually recognize signatures like these?
Most countries have some law covering electronically signed documents — the US ESIGN Act and UETA, the EU's eIDAS regulation, India's IT Act 2000, and similar rules elsewhere. But these laws almost always draw a line between a signature backed by a certificate a recognized authority issued and one you generated yourself. A DSC signed with "Use my certificate" is the kind these laws were built around. A signature from "Create a free signature" cryptographically proves the file wasn't tampered with, but it doesn't get the same automatic recognition — treat it like any other self-signed certificate.
Can I send this to someone else to sign, or track multiple signers?
No — this tool signs a PDF that's already on your device, by you, right now. It doesn't email the file to anyone, collect signatures from other people, or give you a dashboard to track who's signed what. If you need to route a document to several signers and follow its status, you'll need a dedicated e-signature workflow service instead.
How does someone else verify the signature once I send them the file?
They open it in a PDF reader that checks digital signatures — Adobe Acrobat or Reader does this automatically and shows a signature panel with a checkmark or warning icon. Clicking it shows whether the document has changed since signing and who the certificate says signed it. If you signed with "Use my certificate" and the reader already trusts that CA, it shows as verified with no extra steps; a self-signed certificate shows as valid-but-unverified until the recipient chooses to trust it.