How to sign a document electronically

Someone sends you a contract, a form or a lease and asks you to “sign and send it back”. You do not need a printer or a scanner for that. The right method depends on two things: what device you are on and what kind of file it is. Here is the quickest route for each common case.

All the methods below add an image of your handwritten signature to the document — an electronic signature in the everyday sense. That is what “sign and send back” usually means. If you have been asked for a certificate-based signature instead, read what a digital signature is first.

First, look at the file type

• PDF — the easiest case. Almost every phone and computer can sign a PDF with built-in tools.
• Word (.docx) — sign it in Word on a computer, or save it as PDF and sign the PDF.
• Google Docs — sign it in Docs, or download it as PDF and sign that.
• A photo or a paper document — scan it into a PDF first, then sign.

When in doubt, convert to PDF. A signed PDF looks the same on every device, and the signature does not shift when someone else opens it.

On iPhone

Open the PDF in Files, tap the Markup button (the pen icon), then “+” → Add Signature. Draw it with your finger, drag it onto the line and tap Done. A paper document can be scanned first in Notes → Scan Documents. Step by step, with tips for a natural-looking signature, in how to sign a PDF on iPhone.

On Android

There is no single built-in tool on every Android phone, but the free Adobe Acrobat Reader has Fill & Sign: open the PDF, tap Fill & Sign, create a signature with your finger and place it. Some phones also let you draw on a PDF in their built-in file or gallery apps. To turn paper into a PDF, use the scan button in Google Drive (“+” → Scan).

On a Mac

Open the PDF in Preview, click the Markup button, then the Sign button. You can draw your signature on the trackpad, hold a signature on white paper up to the camera, or draw it on a nearby iPhone. Preview saves signatures, so next time it is two clicks.

On a Windows PC

The simplest free option is Adobe Acrobat Reader: Fill & Sign → Sign yourself → Add signature, then type, draw with the mouse or upload an image of your signature. Microsoft Edge opens PDFs too and has a Draw tool, but signing with a mouse that way rarely looks good — an image of your real signature works better.

In Microsoft Word

Insert an image of your signature (Insert → Pictures), set it to In Front of Text and drag it onto the line — ideally a PNG with a transparent background so it does not cover the text. Word for Windows also has a Signature Line feature. Details, plus how to make a neat signature line, in how to add a signature in Word.

In Google Docs

• Draw it: Insert → Drawing → New, choose the Scribble tool from the line menu, sign with the mouse or trackpad, then Save and close. Set the drawing to In front of text and move it onto the line.
• Use an image: Insert → Image → Upload from computer, then place it the same way.
• eSignature: on some paid Google Workspace plans, Docs has a built-in eSignature tool that sends the document for signing and collects signatures for you.

If the other side needs a fixed file, finish with File → Download → PDF.

A document sent as an email attachment

1. Open the attachment and save it — on iPhone, Share → Save to Files; on a computer, download it.
2. Sign it with one of the methods above for your device and file type.
3. Reply to the email and attach the signed file — not the original. Check the file name so you do not send back the unsigned copy.

If the email came from an e-signature service (the message has a “Review and sign” button), you do not need any of this: click the button, sign in the browser and the service sends the signed copy to everyone.

Signing often? Use one app for everything

Built-in tools are fine once in a while. If you sign every week — invoices, timesheets, contracts — an app that keeps your signature and initials saves a lot of tapping. Signature: sign documents for iPhone and Android opens a PDF from Files or a photo of a document, lets you place a signature drawn with your finger on one page, every page or the pages you pick, and saves the result as PDF, JPG or PNG. Save a Word file as PDF first. No account is needed; signing documents comes with PRO.

In short

• Convert to PDF when you can — it is the easiest file to sign and the safest to send.
• iPhone: Files → Markup → Add Signature. Mac: Preview → Markup → Sign. Android and Windows: Acrobat Reader → Fill & Sign.
• Word and Google Docs: insert an image or a drawing of your signature in front of the text.
• An image of your signature is not a certificate-based digital signature — use one only where it is not required.