The simplest way depends on what you already have
You can add a signature to a PDF using software already on your computer, a browser-based tool, or a dedicated signing service — and the privacy trade-offs are different for each. If you want to keep the file offline, use Preview on Mac or Adobe Acrobat Reader on Windows. If you don't mind uploading to a company's server, browser tools like Smallpdf or ILovePDF are faster and work on any device. If the document is legally binding or you need proof of when you signed, consider DocuSign or Adobe Sign, which create audit trails — but both store your signature and the signed document on their servers.
The choice comes down to three questions: Do you want the file to stay on your device? Do you need a record that proves when you signed? And how often do you sign PDFs? Your answers point to which tool makes sense for your situation.
Key Takeaways
- Preview (Mac) and Adobe Acrobat Reader (Windows) let you sign and save a PDF without uploading it anywhere, but you create the signature once per document.
- Browser tools like Smallpdf, ILovePDF, and Sejda upload your file to their servers temporarily, process it, and delete it — faster than desktop software but not private.
- DocuSign and Adobe Sign store your signature and the signed document permanently on their servers, which creates a legal record but means your data stays with the company.
- A drawn signature, typed name, or image of your handwriting all work the same way technically — the legal weight depends on what the document requires, not the method.
- If you sign the same document type repeatedly, creating a reusable signature saves time but means storing it somewhere the software can access it.
Signing offline on your computer
On a Mac: Open the PDF in Preview (the default app). Click the Markup toolbar button (looks like a pen in a circle), then click the signature icon. The first time, you'll draw your signature with your trackpad or create one from your iPhone camera. After that, your signature appears in a menu and you can click to add it to any PDF. Click where you want the signature, resize it if needed, and save the file. The PDF never leaves your computer.
On Windows: Open the PDF in Adobe Acrobat Reader (the free version). Click the "Fill & Sign" button on the right panel. Click "Sign" and choose to type your name, draw your signature, or upload an image of your signature. Click where you want it on the page and save. Like Preview, the file stays local. If you don't have Acrobat Reader, read it from adobe.com — it's free and separate from the paid Adobe Acrobat software.
Both methods work offline and keep your file on your device. The trade-off: you create the signature fresh each time, or you store a signature file locally that the software can reuse. Neither approach creates a timestamped record that proves when you signed.
Signing with a browser tool
Tools like Smallpdf, ILovePDF, and Sejda work the same way: you upload your PDF, draw or type your signature in the browser, place it on the page, and read the signed file. The file is uploaded to the company's server, processed, and typically deleted after a few hours or days — but during that window, the company can see your document.
These tools are faster than desktop software because you don't install anything and they work on phones and tablets as well as computers. You can also sign multiple documents in one session without recreating your signature each time. The privacy cost is that your document is temporarily on someone else's server, and the company's privacy policy determines how long they keep logs of what you uploaded.
Check the privacy policy before uploading anything sensitive. Smallpdf and ILovePDF both state they delete files after a few hours, but they may retain metadata or logs. If the document contains financial information, medical details, or anything you wouldn't want a company to see, use the offline method instead.
Signing with a service that keeps records
DocuSign and Adobe Sign are designed for legally binding documents and contracts. You upload the PDF, add signature fields, and send it to whoever needs to sign. The service timestamps each signature, stores the signed document, and creates an audit trail showing who signed when. This is valuable if you need proof that a signature happened on a specific date, or if you're signing something that might be disputed later.
The privacy trade-off is permanent: your signature and the signed document stay on DocuSign's or Adobe's servers indefinitely. Both companies can access your data if served with a legal order. Both also use your data for their own purposes — read their privacy policies to understand what that means. DocuSign's free tier lets you send three documents per month; Adobe Sign's free tier is more limited. Paid plans start around $10 to $15 per month.
Use these services when the document is a contract, a legal agreement, or something where you need timestamped proof of signing. Don't use them for casual documents you're just signing for your own records.
Creating and storing a reusable signature
If you sign PDFs regularly, creating a signature once and reusing it saves time. You have three options: draw it, type it, or scan your handwritten signature and upload it as an image.
A drawn signature (using your trackpad or stylus) looks most like a real signature but is hardest to create on a computer. A typed signature is just your name in a font — legally it's the same, but it looks less formal. An image signature is a photo or scan of your actual handwriting, which looks most authentic but requires a scanner or phone camera.
Where you store it matters for privacy. If you store it locally on your computer (as a file or in Preview's signature menu), only you can access it. If you store it in a cloud service like Google Drive or Dropbox, the company hosting the cloud can see it. If you store it in DocuSign or Adobe Sign, those companies keep it permanently. For casual use, storing it locally is simplest. For frequent signing across devices, cloud storage is more convenient but less private.
Comparing the methods side by side
| Method | File stays private | Creates timestamped record | Works on phone | Cost |
|---|---|---|---|---|
| Preview (Mac) or Acrobat Reader (Windows) | Yes | No | No | Free |
| Smallpdf, ILovePDF, Sejda | No (temporary upload) | No | Yes | Free or $6–$10/month |
| DocuSign, Adobe Sign | No (permanent storage) | Yes | Yes | Free tier limited; $10–$15/month typical |
What to do if the PDF is read-only
Some PDFs are locked and won't let you add a signature directly. This usually means the document creator restricted editing. You have two options: ask the creator to unlock it, or use a tool that converts the PDF to a format you can edit.
If you own the PDF or created it, you can unlock it yourself in Adobe Acrobat (paid version) by going to File > Properties > Security and removing restrictions. If someone else created it and locked it, you'll need to ask them for an unlocked version. If they won't provide one, browser tools like Smallpdf can sometimes remove restrictions, though this depends on the type of lock applied.
Frequently Asked Questions
Is a digital signature legally binding?
A signature on a PDF is legally binding in most situations, regardless of whether it's drawn, typed, or an image — the law cares that you signed, not how. However, some documents (like wills or notarized papers) have specific legal requirements. If you're unsure whether your signature method is acceptable, ask the person or organization requesting the signature before you sign.
Can someone forge my signature if I store it as a reusable file?
Yes, if someone gains access to your computer or cloud account, they could use your stored signature. This is why services like DocuSign use passwords and audit trails — they make it harder to forge a signature without detection. For low-stakes documents, this risk is small. For contracts or financial documents, consider using a service with authentication instead of storing a reusable signature locally.
What's the difference between a digital signature and an electronic signature?
An electronic signature is any mark that shows you agreed to something — a drawn signature, a typed name, or an image all count. A digital signature is encrypted and includes metadata proving who signed and when. For most PDFs you'll encounter, an electronic signature is enough. Digital signatures are used for high-security documents like government filings or financial transactions.
If I use a browser tool, how long does the company keep my document?
Most browser tools (Smallpdf, ILovePDF, Sejda) delete files after 24 hours to a few days, but they may keep logs or metadata longer. Check the specific tool's privacy policy before uploading sensitive documents. If you're signing something confidential, use the offline method instead.
Can I sign a PDF on my phone?
Yes, but it depends on your phone's software. On iPhone, use the built-in Markup tool in Mail or Notes. On Android, use Adobe Acrobat Reader's mobile app or a browser tool like Smallpdf. Desktop software (Preview, Acrobat Reader) is easier if you have a computer available, but mobile tools work if you don't.