How can I sign PDF on Windows PC without online tools?

Here's how it went.

I'd been putting off signing this PDF—didn't want online tools or paid software—then remembered JSignPdf.

Checked that Java was installed (the one prerequisite you can't skip), grabbed the Windows installer from GitHub, and ran it.

The tricky part: you can't sign without a certificate. I generated a self-signed keystore with Java's keytool—one line, and you've got a .p12 file. For casual signing that's fine; Adobe complains about trust until you mark it trusted, but the signature is valid.

Then the command prompt, the cleanest way once you've done it once:

jsignpdf -kst PKCS12 -ksf mykeystore.p12 -ksp mypassword -V -pg 1 -llx 50 -lly 50 -urx 250 -ury 120 mydocument.pdf

-V gives a visible signature, and the four coordinate flags draw the stamp box on page one. Drop them for an invisible signature. Either way, JSignPdf outputs a _signed.pdf next to your original.

Maybe ten minutes total, most of it second-guessing the keytool command. If you're wondering how to sign PDF files on Windows without a browser or subscription, this is a solid offline route—just be ready to wrestle with the certificate first. Once the command's saved, how to sign PDF next time is a copy-paste job.

The self-signed warning in Adobe is the only annoyance, but for everyday forms it's not a dealbreaker.