What this tool does
Sign PDF lets you draw a signature in your browser and stamp it onto any page of a PDF. You pick the page, pick a position from a six-cell grid, set the width, and click Apply. The signature embeds as a transparent PNG using pdf-lib. Nothing about your file or your signature image ever leaves the browser tab — no upload, no server round-trip, no account, no waiting in a queue.
That's the whole product. It is not a hosted e-signature service, it does not have an inbox of pending signers, it does not email a copy to a counterparty. You sign your own PDF, you download the signed file, you do whatever you want with it.
Read this before you sign anything important
This matters enough that we put it ahead of the how-to, because some readers will skim. A drawn signature stamped onto a PDF — what this tool does, what every "free PDF signer" on the web does — is not a legally certified e-signature. There is no cryptographic chain of custody, no identity verification, no timestamp from a trusted authority, no audit trail of who clicked what at what IP address. It's an image of your handwriting glued on top of a page.
If the document is legally binding — employment contract, real-estate paperwork, anything you need to hold up in court — use DocuSign, Adobe Sign, or HelloSign. Those services issue certified signatures with an audit trail that names you, your IP, and the exact second you signed. That audit trail is the whole product. Sign PDF, by contrast, is for casual signing where a visible signature is what's needed: internal forms, informal letters, a tax-prep cover sheet, an HR doc your team trusts you on, a permission slip for your kid's field trip.
This is the same standard you should apply to every browser-based PDF signer. The vendor matters less than what the signature actually is at the byte level. If your bank wouldn't accept it, you probably shouldn't either.
How to sign a PDF
The flow is built for the most common case: signing the last page of a contract.
- Drop or pick your PDF. Up to 100 MB. The tool reads the page count and defaults the signature placement to the last page, since that's where almost every signature lives.
- Draw your signature in the canvas pad. Mouse, trackpad, finger on a touchscreen, stylus on a tablet — all work. The pen uses a 2.5pt stroke with round caps and joins, so the line reads as natural handwriting, not a jagged pixel scribble. Click Clear signature to redo.
- Pick the page and the position. Six grid cells per page (top-left, top-center, top-right, bottom-left, bottom-center, bottom-right). Bottom-right is the default because that's where most signature lines sit.
- Adjust the width if needed. The default is roughly 180 pt, which is 2.5 inches at 72 dpi — about the size of a hand-written signature on lined paper. Most signature boxes accommodate that.
- Click Apply signature. Download. Output:
contract.pdfbecomescontract-signed.pdf.
If you need to sign more than one page, or you need a separate set of initials alongside your full signature, run the tool twice. Apply your signature, download, drop the result back in, draw again, sign another page. Each pass is a fresh stamp on the PDF — the previous signature stays put because it's already baked in.
Where to put the signature: the six positions
The grid is deliberately coarse. Six positions covers the cases that actually exist in real contracts; finer positioning invites people to spend ten minutes nudging a signature by two pixels. Pick a cell, ship the file.
| Position | When to use it | Typical width |
|---|---|---|
| Bottom-right | Standard contract signature line. The default for a reason. | 180 pt |
| Bottom-center | Forms with a centered signature field (waivers, permission slips). | 180 pt |
| Bottom-left | Two-party contracts where the second signature goes here. | 180 pt |
| Top-right | Cover-letter style "approved by" stamp on the first page. | 140 pt |
| Top-center | Memo header signature blocks. | 140 pt |
| Top-left | Less common; works for letterhead with a signature near the date. | 140 pt |
If none of the six cells lines up cleanly with the printed signature line, the tool also lets you change the width. A narrower signature (say 120 pt) drops into a tighter box; a wider one (240 pt) fills the whole right half of a footer. The placement still snaps to a grid cell, but the size adjusts.
A worked example
Here's a real run. You receive a one-page consulting agreement called agreement-2026-05.pdf — three paragraphs, a signature line at the bottom-right that says "Consultant: ____________________ Date: __________." The line sits about an inch from the right margin and an inch from the bottom of the page.
You drop the file in. The pad shows page 1 of 1, signature destination defaults to page 1, position bottom-right, width 180 pt. You draw your signature in the canvas (takes three seconds). You don't need to change anything else — bottom-right at 180 pt is exactly where that signature line is. Click Apply, click Download. The output, agreement-2026-05-signed.pdf, has your handwritten signature sitting on top of the signature line at the bottom-right. Total time from drop to download: under thirty seconds.
You email it back to the counterparty. If they want a certified, audit-trailed version on top, that's their workflow — they can upload your signed PDF to their DocuSign instance for their own counter-signing. Your part of the job is done.
Why drawn, not typed in a cursive font
Most online PDF signers offer a "type your name and we'll render it in a script font" option. We deliberately don't. A typed cursive signature looks fake to anyone who's seen more than three of them — the letters are too even, the slant is too uniform, the connections between letters don't match how humans actually write. It signals "I generated this on a website" in a way that erodes whatever trust the document carries.
Drawing on the canvas, even with a mouse, produces something that reads as a real signature. It's not pretty, but it's yours, and it varies the way handwriting varies. If you have a tablet and a stylus, the result is essentially indistinguishable from a pen on paper. If all you have is a laptop trackpad, your signature will look like a trackpad signature — which is fine, because that's the same signature you'd produce on a tablet at the bank.
Why no upload — and why we make a point of it
Most "free PDF signer" tools work by uploading your file to a server, processing it there, and giving you back a download link. iLovePDF and SmallPDF both do this. Their privacy policies generally promise to delete the file within an hour or two. Reasonable enough — until you remember that you just sent your signed contract, with your handwritten signature on it, to a third-party server in a country whose data laws you haven't read.
Sign PDF does the signing in your browser with pdf-lib. Your PDF bytes are read into JavaScript memory, the signature canvas exports a PNG into the same memory, pdf-lib embeds the PNG into the PDF, and the result is downloaded as a Blob — never as a network response from a server, because there is no server. Open your browser's network tab and watch: not a single byte of your PDF leaves the tab during the sign and save steps.
That's not a privacy promise. It's an architecture. There's nothing to honor or violate, because the path that would carry your file to a server doesn't exist.
What about Adobe Acrobat?
Adobe Acrobat Pro has a Fill & Sign tool that does roughly what this tool does — draw a signature, stamp it on a page — plus a hundred other things. Acrobat Pro costs about $20 a month. If you sign one PDF every six weeks, that's a strange subscription. If you sign PDFs daily and need form-field detection, advanced redaction, OCR, and a real e-signature workflow with Adobe Sign, Acrobat Pro is the right tool. For the case in between — occasional casual signing — Sign PDF does that one job and stops.
The same logic applies to DocuSign and HelloSign. They are the right answer when you need a legal audit trail. They are overkill when you just need to put your name on a permission slip.
Related PDF tools
Sign PDF is one move in a small toolkit. The neighbors:
- PDF Watermark — stamp text or an image (DRAFT, CONFIDENTIAL, your company logo) across pages. Same engine, different shape.
- Add Page Numbers to PDF — useful when you've combined documents and need consistent numbering before signing.
- Flatten PDF Form — bake form-field values into static page content so the signed copy can't be edited.
- PDF Merger — combine a signed cover page with the underlying agreement.
- Split PDF — pull out just the signature page from a long contract if that's all you need to share.
Frequently asked questions
Is this a legally binding e-signature?
No. A drawn signature is an image embedded in the PDF — there's no cryptographic proof of who signed, no verified timestamp, no audit trail. For binding documents that may end up in court, use DocuSign, Adobe Sign, or HelloSign. Those services issue certified signatures with signer authentication and a verifiable audit trail. Sign PDF is for casual signing: internal forms, informal letters, low-stakes paperwork where a visible signature is what's needed.
Is my PDF really not uploaded anywhere?
Correct. The signature canvas runs in your browser; pdf-lib embeds the image and writes the new PDF locally. Zero outbound requests during sign or save. Open your browser's network tab and confirm — neither the PDF nor the signature image ever leaves the tab.
Can I sign multiple pages at once?
Not in one operation. Each apply targets one page. To sign multiple pages, apply your signature, download, drop the signed PDF back in, draw the signature again, and sign another page. Tedious for many pages, fine for two or three. Multi-page signing in a single pass is on the roadmap.
Can I add initials in addition to a full signature?
Yes, by running the tool twice. Sign with your full signature, download, drop the result back in, draw your initials this time, place them on whichever page needs them. The previous signature stays embedded because it's already part of the PDF.
Will the signature look professional?
It will look like your handwriting. The canvas uses a 2.5pt stroke with round caps and joints, which renders smooth natural-looking lines rather than jagged pixels. With a stylus and a tablet, the result is essentially the same as a pen signature on paper. With a mouse, it looks like a mouse signature — which is fine, because that's what readers expect from a browser-based signer.
Does it work on a phone?
Yes. The canvas uses pointer events, which cover touch, mouse, and stylus on the same code path. Finger-drawing on a phone is workable for casual signing; for cleaner output, a tablet plus stylus is better.
What about password-protected PDFs?
pdf-lib refuses to open encrypted PDFs. Unlock the file in a desktop reader first (Preview, Adobe Reader, or your password manager's PDF tool), then bring the unlocked version here.