Sign a PDF without uploading the contract
Of everything people do to a PDF, signing is the one where handing the file to a stranger makes least sense. The documents that need a signature are offers of employment, tenancy agreements, NDAs, consent forms, invoices — documents that carry names, addresses, salaries and bank details. The standard advice is to upload one to a website, and it has always been a strange thing to recommend.
This tool removes the step. The PDF is opened by your browser, the page you are signing is rendered on your own screen, and your signature is drawn into the page in local memory. The site is a set of static files with no server that could receive a document even if it wanted to.
Drawn or typed
Drawing gives the closest thing to your real signature and works with a finger on a phone or tablet, a stylus, a trackpad or a mouse. Strokes are smoothed as you draw, and the result is trimmed to the ink so the mark you place is the mark you see.
Typing renders your name in a handwriting style. It is faster and more legible, and it is what most people choose on a laptop. Because it uses the fonts on your own device, the preview is authoritative — what is shown is what gets stamped.
Either way the signature is saved as a transparent image, so it sits on the page rather than covering it with a white rectangle — the difference between signing a document and pasting a sticker onto it.
What an electronic signature is, and is not
A visible signature on a document is the electronic counterpart of signing in ink, and it is what the overwhelming majority of agreements actually use. Under the US ESIGN Act and the EU's eIDAS regulation a signature is not denied legal effect merely for being electronic.
It is a different thing from a digital signature in the cryptographic sense, where a certificate is bound into the file so that any later alteration can be detected. That requires a certificate authority and an identity check, which a tool that runs only in your browser cannot honestly provide. If your situation calls for a qualified electronic signature or a tamper-evident audit trail, use a service built for it. Most situations do not.
Related tools
To lock the signed document so it cannot be opened without a password, follow this with Protect PDF. To mark it as a draft or a copy, use Watermark PDF. To combine it with attachments, use Merge PDF.