How do you sign a PDF without uploading it?

There is no way you can sign a PDF in Windows without uploading it. In macOS, you have the ability to eSign a document with Preview, but your signatures won't be legally binding. Moreover, you won't always have your Mac at hand. Consider using a professional eSignature solution – airSlate SignNow. You can access your account from any device, whether it be a laptop, mobile phone, or tablet. Utilizing applications can improve your user experience, but it's not obligatory. Try the web-version, try the app, and make your choice.