Apply a verifiable digital signature (PKCS#7/X.509, compliant with ISO 32000) to your document — all processed in your browser, without sending the file anywhere.
Everything is processed in your browser — the PDF and the private key never leave your computer.
Choose the document that needs a cryptographically valid digital signature.
Generate a (self-signed) digital certificate or upload an existing one, and set the signer's details.
The PDF is digitally signed — any PDF reader can verify the signature and detect whether the file was changed after signing.
"Fill and sign" overlays an image of your handwritten signature — it's visual. This tool applies a cryptographic digital signature that any PDF reader can verify, and that automatically detects whether the document was changed after signing.
It depends on the type of certificate used. A self-signed certificate proves the document's integrity but not the signer's legally verified identity; for full legal validity (equivalent to a qualified signature), you need a certificate issued by a recognized certification authority.
Any modern PDF reader (such as Adobe Acrobat Reader) automatically shows the digital signature status when opening the file, including whether the document was modified after it was signed.
No. All processing happens inside your own browser — the file never leaves your computer or passes through any external server. You can confirm this by disconnecting from the internet once the page has loaded: the tool keeps working normally.
No. PDFsy doesn't ask for sign-up, an account or payment — just open the page and use the tool.
Yes. PDFsy offers PDF tools equivalent to iLovePDF's — merge, convert, compress, protect and much more — available in 25 languages, with no usage limits, no need to create an account, and 100% local processing in your browser, without uploading any file to any server.