How to Sign a PDF: Every Method for Mac, Windows, Phone, and Free Online

Signing a PDF is the process of adding your name, in a drawn, typed, or uploaded form, to a document so it counts as a real, legally recognized signature. Every major operating system released since the early 2010s ships with a built-in way to do it, no download required. Mac has Preview, Windows has Edge, and iPhone and Android handle it through apps you already use.

Somebody just emailed you a PDF and asked for your signature by end of day. No printer, and buying Adobe Acrobat for one document feels absurd. Good news: you almost certainly already own everything you need. This guide walks through all five methods, tells you which fits your situation, and closes with the question everyone eventually asks: is any of this legally binding?

Short version first, pick based on your device and what you're signing.

1. 1
   Mac: Open the PDF in Preview, click the Markup icon, then Sign.
2. 2
   Windows: Open the PDF in Microsoft Edge (the default PDF viewer), use the Draw tool.
3. 3
   iPhone/iPad: Open the file in Files or Mail, tap the Markup pen icon, add your signature.
4. 4
   Android: Open the PDF in Google Drive, use the annotate tool to draw your signature.
5. 5
   Free online, no install: Use a browser-based tool like Chaindoc's document signing or Adobe's free Fill & Sign when you're on a shared computer.

Notice what's missing from the table above: a "best overall" crown. There isn't one, the right method depends on what device is in front of you and whether you need a quick scribble or something with more legal weight behind it.

Mac users have it easiest. Preview has supported PDF signing for over a decade and works without opening any other app.

1. 1
   Open your PDF in Preview (macOS's default viewer, unless you've changed it).
2. 2
   Click the Markup toolbar icon, a pen tip inside a circle, near the top-right.
3. 3
   Click Sign in the Markup toolbar.
4. 4
   Choose how to create your signature (three options below).
5. 5
   Click your saved signature, then drag and resize onto the signature line.
6. 6
   Save (Cmd+S), or export a copy to keep the unsigned original.

Step 4 gives you three ways in. Trackpad: sign with your finger, press any key when done, fastest but least polished. Camera: sign on plain paper, hold it to your Mac's camera, align with the blue guideline; Preview turns it into a transparent image with real handwriting fidelity. iPhone or iPad: if your devices share an Apple ID and sit nearby, choose "Select Device" and sign on its screen with your finger or Apple Pencil, per Apple's Preview guide. That signature then stays saved for every future PDF.

Windows lacks a direct Preview equivalent, but Microsoft Edge handles PDFs by default on Windows 10 and 11, and it includes a built-in Draw tool made for exactly this job. No separate app, no download, and no Microsoft 365 subscription required, just the browser that ships with the operating system.

1. 1
   Open the PDF file. If Edge is your default handler, double-clicking opens the browser-based viewer.
2. 2
   Look for the annotation toolbar near the top (icons shift between Edge updates, so look for a pen icon rather than a memorized spot).
3. 3
   Select the Draw tool and pick a thin line weight, this reads as a signature, not a doodle.
4. 4
   Draw your signature with your mouse, trackpad, or touchscreen.
5. 5
   Adjust color and thickness if needed, then click outside the drawing area to place it.
6. 6
   Save with Ctrl+S, or "Save As" to keep an unsigned copy.

Edge's toolbar changes layout more often than Preview's, so the click sequence might shift slightly, but drawing onto a PDF has stayed stable regardless. On a locked-down work laptop, this is genuinely your best option: zero admin rights, zero downloads, though it only produces a drawn signature, not a certificate-based one.

If the PDF landed in Mail or Files, iOS's Markup tool signs it without installing anything extra, and it has worked essentially the same way since iOS 9 introduced Markup back in 2015. That kind of stability is rare for a mobile feature and means the steps below hold up across older devices too.

1. 1
   Open the PDF in Files, or the email attachment directly in Mail.
2. 2
   Tap the Markup icon, a pen tip inside a circle, top-right of the screen.
3. 3
   Tap the + button, then select Signature.
4. 4
   If you've signed before, your saved signature appears, tap to insert. Otherwise draw a new one with your finger or Apple Pencil.
5. 5
   Drag it into place, resize with the corner handles, then tap Done.

Mail has a nice shortcut: open a PDF attachment right inside Mail, mark it up, hit reply, the signed version attaches automatically. One honest limitation: Markup signatures are drawn images, not certificate-based ones, fine for a signed NDA or quick approval, but not for a document requiring a qualified electronic signature.

Android has no single universal built-in signer the way iOS has Markup, largely a side effect of how fragmented the Android device landscape is across manufacturers. Google Drive's PDF viewer covers the basic case reasonably well, though, and a 2024 Google I/O developer report put active Android devices past 3 billion, with Drive installed by default on nearly all of them.

1. 1
   Open the PDF in Google Drive (upload it first if needed).
2. 2
   Tap the pen or annotate icon in the toolbar (position varies by Drive app version).
3. 3
   Select the drawing tool and draw your signature with your finger.
4. 4
   Tap the checkmark or "Save" icon, then share or download the signed file.

If Drive's tool feels clunky, third-party apps fill the gap fast, most PDF reader apps on the Play Store include a basic free signature feature. Just check review counts before installing the first result.

Adobe invented the PDF format back in 1993, so it's no surprise its free reader app handles signing well, identically across Windows, Mac, iOS, and Android. Acrobat Reader remains one of the most-downloaded free apps in both major mobile app stores, largely because so many PDFs still originate from Adobe's own tools.

1. 1
   Open your PDF in Adobe Acrobat Reader (free download if you don't have it).
2. 2
   Click Fill & Sign from the right-hand tool panel, or the Tools menu on mobile.
3. 3
   Click the Sign icon (a pen nib), then choose Add Signature or Add Initials.
4. 4
   Type, draw, or upload an image, whichever looks closest to your real signature.
5. 5
   Click Apply, then click the document to place it. Drag to reposition, resize with the corner handles.

Here's the split that matters: Fill & Sign is genuinely free for basic signing, checkmarks, and text fields, no paywall, no trial expiration. What's NOT free: certificate-based digital signatures, sending documents out for others to sign, or editing the underlying PDF content, those live behind Acrobat Standard or Pro. Check Adobe's Fill & Sign documentation for the current breakdown.

Sometimes none of the above works. Public library computer. Chromebook. Company IT policy blocks new installs entirely. A browser-based signing tool solves that without touching your device's software.

The category includes names you've probably seen: Adobe's web-based Fill & Sign, Canva's document tools, iLovePDF's signature feature, and Chaindoc's online document signing, among others. They follow roughly the same pattern: upload your PDF, draw or type a signature, download the signed file, under two minutes.

What differs is what happens after signing. Some tools hand back a flattened PDF with an image pasted on it, no different in legal weight from a Markup signature. Others, Chaindoc included, attach a verifiable audit trail, timestamped and tied to the signer's identity, so the record can't be quietly altered later. That barely matters for a one-off form. It matters a lot for a contract that might get disputed, which is where a platform like Chaindoc's document signing workflow pays for itself.

Short answer: yes. In the US, a drawn or typed signature on a PDF is legally binding in the overwhelming majority of everyday situations. Not a gray "probably fine" area, it's settled law.

According to the official text of the ESIGN Act, passed in 2000, electronic signatures carry the same legal weight as ink signatures for most contracts. States separately adopted the Uniform Electronic Transactions Act (UETA), and 49 states plus the District of Columbia have enacted some version of it (New York relies on its own similar statute instead). Together, ESIGN and UETA are why every method here, trackpad scribble, Markup drawing, uploaded image, counts as a real signature, as long as three things hold true. Intent to sign: deliberately drawing your name, not an accidental click. Association with the record: the signature has to logically tie to the specific document, which placing it on the signature line inside the PDF handles. Retention: the file needs storage in a reproducible form, which a saved PDF satisfies on its own.

Where guides oversimplify: a drawn signature isn't a certificate-based digital signature (PKI/X.509 cryptography). Some situations specifically require that, certain government filings, regulated financial or healthcare transactions, anything needing genuine cryptographic non-repudiation, mathematical proof the signature wasn't altered, not just a reasonable assumption.

For most contracts, NDAs, and everyday business paperwork, a drawn signature from any method here holds up fine. Not sure which category yours falls into? Ask whoever's on the other end of the request, or your own counsel.

You've signed the document, or received one signed by someone else. How do you confirm it's real and hasn't been tampered with since?

For certificate-based signatures, most PDF readers show a verification badge automatically, Adobe Acrobat displays a blue ribbon at the top of a digitally signed document, and clicking it reveals certificate details and validity.

For drawn signatures with an attached audit trail, like those from Chaindoc's signing flow, there's no certificate baked into a simple image overlay, so verification works differently: check the audit record instead, who signed, the timestamp, confirmation the content hasn't changed. Chaindoc's free PDF signature verification tool does exactly this, upload any signed PDF and it checks whether the recorded signature and timestamp still match. A signature that looks fine to the eye tells you nothing about whether the file got edited after signing; verification tools check actual file integrity, not just whether a signature-shaped image sits on the page.

Signing your own lease renewal or a doctor's office form? Any built-in method, Preview, Edge, Markup, works in under a minute, don't overthink it.

Sending a contract to a client, freelancer, or vendor who needs to sign and send it back? That's when a dedicated e-signature platform earns its keep, beating manually emailed PDFs. Chaindoc's document creation tools build the contract and collect the signature in the same flow.

Working with something that carries real legal weight, an employment contract, a regulated financial document, anything where a later dispute gets expensive? Stop improvising with a drawn signature and confirm what your document and jurisdiction actually require. The tools here answer "does this count as signed," they don't replace legal judgment on high-stakes paperwork.