Sign PDF (Add Signature) - Step by Step
Sign PDF (Add Signature) runs in three steps: open the tool, choose the PDF and signature image, then download the signed file. This page walks through what each step expects.
Step 1 - open the tool
Go to Sign PDF (Add Signature). Nothing needs to be installed or signed in before you start.
Step 2 - choose the PDF and signature
Choose a PDF file, then choose a PNG or JPG signature image. Pick the page number and corner (bottom-right by default), then click Sign PDF. Both files stay in this browser tab - nothing is uploaded to a server.
Step 3 - download the result
When the status line says the signed PDF is ready, click Download PDF to save signed.pdf. The original files are not kept beyond the page session.
Signature size and position on the page
The corner picker offers four fixed positions - bottom-right, bottom-left, top-right, top-left - and bottom-right is selected by default. Whichever corner you pick, Sign PDF (Add Signature) auto-scales the signature image to fit within whichever is smaller: 180pt, or 35% of the target page's own width. The height is scaled by that exact same ratio, so the signature keeps its original aspect ratio and is never stretched wide or tall to fill the corner. A fixed 24pt margin is kept between the signature and the edge of the page in every corner, so the mark never touches the page border.
What happens when something does not match
Two checks run automatically before the signed file is produced. First, once you choose the PDF, the page-number field's upper limit is set from that file's real page count, read live from the PDF itself - not guessed from its file size. If you click Sign PDF with a page number past that real count, the tool stops and names the PDF's actual page count in the status line instead of failing silently. Second, the signature file's PNG-versus-JPG format is first guessed from its filename and MIME type; on the rare file where that guess is wrong, the tool automatically retries with the other image codec before it ever shows you an error, so a mislabeled file extension does not by itself block the signing.
Frequently Asked Questions
Can one signing pass put the same signature on more than one page?
No. Each run signs exactly one page - the page number you choose is applied once, and there is no loop that repeats the same signature across multiple pages in a single pass. To sign a second page, run the tool again on the already-signed download and pick the next page number.
What happens if I type a page number the PDF does not have?
The tool refuses to guess. Because the page-number field's maximum is set from a live read of the PDF's actual page count, clicking Sign PDF with a number above that count stops the run and states the file's real page count in the status line, rather than producing a corrupted or blank result.
Do I need to check whether my signature file is a PNG or a JPG before uploading it?
No. The tool guesses the image codec from the file's name and MIME type first, and if that guess turns out wrong for the actual file contents, it automatically retries with the other codec (PNG or JPG) before showing any error. Only a file that fails both attempts is rejected.
Can I drag the signature to a different spot after it has been placed?
No. There are no drag or resize handles in the result - the corner and the size cap are both fixed at the moment you click Sign PDF. To move or resize a signature, run the tool again with a different corner choice, or with a signature image that is already cropped or resized the way you want it.
Does this create a legally certified or cryptographically signed PDF?
No. The tool places one signature image on one page at a fixed corner - it does not draw freehand on the document, does not fill in a PDF's built-in AcroForm signature fields, and does not cryptographically certify or lock the file the way a digital-signature certificate service would.
Will a small signature image be stretched up to fill the size cap?
No. A signature image already smaller than the 180pt / 35%-of-page-width cap is placed at its native size - the scaling math only ever shrinks an oversized image down to fit, it never enlarges a small one, so a compact signature stays exactly as crisp as the file you uploaded.
Why trust these tools
- Ten-plus years of web tooling. The freetoolonline editorial team has shipped browser-based utilities since 2015. The goal has never changed: get you to a working output fast, without an install.
- No install, no sign-up. Open a tool and get a working output in seconds - nothing to download and no account to create. Tools that need heavy processing run it on our service, so even a low-powered machine gets the job done.
- Analytics stops at the page view. We measure which pages get visited, not what you type or upload inside a tool. There is nothing to sign in to and no profile is attached to your input.
- Open-source core components. The processing engines underneath (libheif, libde265, pdf-lib, terser, clean-css, ffmpeg.wasm, and others) are public and audit-able. We link to each one in its tool page's footer.
- Free, with or without ads. All tools are fully functional without sign-up. The Disable Ads button in the header is always available if you need a distraction-free run.