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PDF加密/解密
为PDF设置密码保护或移除密码保护
拖拽PDF文件到此处，或点击选择
最大文件大小：128 MB
所有处理均在浏览器本地完成，文件不会上传到服务器。
免费密码保护 PDF — 无需付费使用 AES-256 安全保护
Add professional-grade password protection to any PDF — entirely free. AES-256 encryption, browser-side processing, no daily limits, no watermarks, no sign-up. Whether you secure one document or one hundred, our tool is ready. Replaces paid alternatives like Adobe Pro for this specific task.
100% FreeNo UploadNo Sign-up100% Free, No Limits
使用步骤
- Drop PDF: Drag any PDF in. Multi-page documents supported. The tool shows file size and confirms the PDF is ready for encryption.
- Set Strong Password: Enter a password. We recommend 12+ characters with mixed case, numbers, and symbols. Password length matters more than complexity — passphrases like 'correct-horse-battery-staple' are excellent.
- Optional Restrictions: Decide whether to restrict printing, copying, or editing. For maximum compatibility, leave restrictions off and rely on the open password alone.
- Encrypt: Click 'Encrypt'. Your PDF is encrypted in your browser with AES-256. The output downloads as a new file. Process 1, 5, or 100 documents — no usage limits.
为什么选择此工具
- 100% Local Processing: Files are processed entirely in your browser using JavaScript — never uploaded to any server.
- No Limits: No file count or file size restrictions. Process as many files as your device can handle.
- No Sign-up: Free forever, no account needed, no email required. Open the page and start.
- Private by Design: Nothing is sent to any server. Close the tab and your files are gone forever.
常见问题
Can I password protect a PDF for free?
Yes — our PDF Encrypt tool is 100% free with no sign-up, no daily limits, no watermarks. Drop your PDF, set a password, click 'Encrypt'. The encrypted PDF downloads immediately. We use AES-256, the same encryption standard as paid tools like Adobe Pro.
Is this as secure as Adobe Pro?
Yes for the encryption itself. Adobe Pro uses the same AES-256 standard that we use. The difference: Adobe offers additional features (digital signatures, certificate-based encryption, redlining tools) that we don't. For password-based protection, our output is identical in security strength.
How is this free without ads or selling my data?
We use opt-in non-intrusive advertising on some pages, and premium sponsored positions. We never sell user data, never upload files (everything is browser-side), and never limit usage to force a paid tier. PDF protection is a basic document utility — it should be free for everyone.
Will my PDFs be uploaded?
No. Encryption runs entirely in your browser via pdf-lib + Web Crypto API. Your PDF and your password stay on your device. Only the encrypted output saves locally.
Can I protect many PDFs at once?
Yes — drop multiple PDFs and the tool processes them sequentially. You get a ZIP of encrypted PDFs (each with the same or different passwords, your choice). No limit on batch size other than your device memory.
What if I forget the password?
Recovery is impossible by design — AES-256 with a strong password cannot be brute-forced. If you forget the password, the encrypted PDF is effectively inaccessible. Always store passwords in a password manager (1Password, Bitwarden, LastPass) or in a secure written record.