At some point almost everyone gets emailed a PDF — a lease, a freelance contract, a consent form, an acknowledgment of receipt — with a note that says "please sign and return." For years the only realistic option was to print it, sign it with a pen, scan it back in, and email the scan, which is a surprising amount of friction for what is often a thirty-second task. Modern browsers and a handful of built-in operating system tools make it possible to skip the printer entirely. This guide walks through signing a PDF with Dagochim's free Sign PDF tool, covers the signature options built into Windows and Mac, and spends real time on a question people often skip past too quickly: what does a signature like this actually mean legally, and when should you reach for something more robust instead?
When you'd reach for this
- Signing a rental agreement, freelance contract, or vendor form that arrived as a PDF attachment
- Filling out a consent form, waiver, or participation form that includes a simple signature line
- Initialing or signing an internal company document to confirm you've read it
How to sign a PDF with Dagochim
- Open the Sign PDF tool and drop in the PDF you need to sign.
- Create a signature using one of three methods: draw it with a mouse or your finger on a touchscreen, type your name and have it rendered in a chosen font, or upload a photo of a signature you already have on paper.
- Click "Add signature" to place it on the page, then drag it into position and resize it from the corner handle to fit the signature line.
- Add a date stamp if the form calls for one, and if the document needs a signature on more than one page, move to the next page and add another.
- Click "Save signed PDF" to download the finished file, ready to email back.
What this signature actually means, legally
This is worth reading carefully before you sign anything that matters. Under Korea's Electronic Signature Act (전자서명법, fully revised in 2020 when the old "공인인증서"/certified-signature-authority system was abolished), an electronic signature is not automatically denied legal effect merely because it exists in electronic form (Article 3). The Act defines an electronic signature as electronic information attached to or logically combined with an electronic document, used to show the signer's identity and the fact that the signer signed that document (Article 2, item 2). The signature Dagochim's Sign PDF tool creates is a visual signature: a drawn, typed, or uploaded image placed on top of the PDF page. It does not independently verify who the signer is, and it includes no tamper-evidence mechanism to prove the document wasn't altered after signing. That means if a signature were ever disputed, proving both who actually signed and that nothing changed afterward typically requires additional safeguards — identity verification, timestamping, cryptographic tamper detection — that this tool, and in fact most simple "draw a signature" tools of any kind, do not provide on their own. This is not unique to Korea either: in most jurisdictions, a plain signature image generally carries less evidentiary weight in a dispute than a signature created through a certified e-signature platform with a full audit trail (who signed, when, from what device, with what identity check), or an original wet-ink signature on paper. For contracts, legal filings, HR documents, or anything you might need to prove was signed by a specific person at a specific time, use a certified e-signature service — providers such as DocuSign, Adobe Acrobat Sign, and Korea's Modusign all build in identity verification and tamper-evidence — or sign the physical document by hand. For lower-stakes situations — acknowledging you read an internal memo, initialing your own worksheet, filling out a casual form, signing something purely for your own records — a visual signature like this one is genuinely fine, and far faster than printing, signing, and rescanning.
Windows: using the Microsoft Edge PDF reader's Draw tool
Windows doesn't ship with a dedicated "sign a PDF" feature, but if you're on Windows 10 or 11, Microsoft Edge is typically set as the default PDF viewer, and its built-in PDF reader includes editing and annotation tools without needing to install anything extra. According to Microsoft's own Edge Learning Center documentation and Microsoft Q&A support threads, the process is: open the PDF in Edge (double-click it, or drag it into an Edge window), click the Draw button in the toolbar, choose a pen color and thickness, then sign using your mouse, a touchscreen, or a stylus directly on the page. Click Save in the toolbar afterward to keep the signed version. This works well for a quick, casual signature, though it's worth knowing the ink is literally drawn onto the page rather than placed as a movable, resizable object the way Dagochim's tool handles it — so if your first attempt looks messy, you may need to use Edge's eraser or undo and try again rather than nudging it into place afterward. A small number of users have also reported bugs in various Edge versions where drawn ink briefly disappears before saving; if that happens, try again with the mouse instead of a stylus, or fall back to a tool like this one that treats the signature as a separate, draggable layer instead of permanent ink.
Mac: signing with Preview's trackpad, camera, or iPhone/iPad
macOS handles this more smoothly through the built-in Preview app, and Apple documents the feature directly in its official support guide for filling out and signing PDF forms in Preview. Open the PDF in Preview, show the Markup toolbar if it isn't already visible, and click the Sign button. From there you can create a signature three ways: sign your name on the trackpad with your finger, hold a paper signature up to your Mac's built-in camera so Preview captures it digitally, or use a nearby iPhone or iPad as a signing pad with your finger or an Apple Pencil, provided that device meets Apple's Continuity requirements. Once a signature is captured, it's saved inside Preview (and synced via iCloud Drive to your other Macs), so the next time you need to sign something you can simply click the Sign button again, pick the existing signature, and drag it into place with the blue resize handles — no need to redraw it from scratch every time. Preview only signs PDFs and images directly, so if you've been sent a Word document that needs a signature, save or print it to PDF first, then open that PDF in Preview to sign it.
Making your signature image look cleaner
If you're photographing a paper signature to upload, write it large with dark ink on plain white paper, and take the photo in even lighting without shadows or glare so the edges stay sharp. After uploading to Dagochim's tool, turn on Remove white background so the white paper around your signature becomes transparent rather than sitting on the page as an opaque rectangle. If you draw your signature directly on the built-in canvas instead, the empty margin around your strokes is trimmed automatically, so drawing a bit larger in the center of the box tends to look better once it's placed and scaled down to fit a signature line. Save a signature image you like as a PNG file once, and you can re-upload the exact same file the next time you need to sign a different PDF, rather than redrawing or rephotographing it every time.
Is my document safe?
Yes. Dagochim's Sign PDF tool never uploads your file, or your signature image, to a server — everything happens locally inside your browser tab. Contracts, personal information, and the signature itself all stay on your own device throughout the process.
Frequently asked questions
Is this a certified electronic signature?
No. Dagochim's Sign PDF tool places an image on top of the page. It has no identity verification or tamper-evidence, so it is not a certified e-signature service. Use a certified e-signature platform or a handwritten signature for documents where legal effect really matters.
Can I sign a PDF with built-in Windows tools?
Windows has no dedicated signature feature, but the Microsoft Edge PDF reader includes a Draw annotation tool: open the PDF in Edge, click Draw, choose a pen and thickness, sign with a mouse, touchscreen, or stylus, then click Save.
How do I sign a PDF on a Mac?
The built-in Preview app can capture a signature using your trackpad, your Mac's camera pointed at a paper signature, or a nearby iPhone or iPad, then let you drag that saved signature onto any PDF from the Markup toolbar's Sign button.