How to Sign a PDF on Android: 3 Free Ways

1. In Chrome, no app (MultiDocs)

This is the same on every Android phone because it runs in the browser, and it's the only one of the three that adds a record of the signature.

1. Open multidocs.app/sign-pdf in Chrome (or any browser).
2. Tap “Choose document” and pick the PDF from Downloads, Drive or your files. You can also choose a photo, or tap “Scan a paper document” to use the camera.
3. Choose “Just me” and tap “Add my signature.” Draw it with your finger.
4. Tap the spot on the page where it goes. Add your printed name, the date or a checkbox if needed.
5. Tap “Finish” and download the signed PDF, or send it by email.

It's free and unlimited, with no watermark. When only you sign, the document is processed on your phone and never uploaded. The signed PDF has a last page with the date, time and SHA-256 fingerprint of the document, which can be checked at /verify.

2. Adobe Acrobat Reader app

If you sign PDFs often and want a saved signature on your phone, Acrobat Reader is free on Google Play.

1. Install Adobe Acrobat Reader from Google Play and open the PDF with it (from your files, tap the PDF › Open with › Acrobat).
2. Tap “Fill & Sign” in the bottom menu.
3. Tap Signature › Add signature. Draw it and tap “Done.”
4. Tap where the signature goes, then drag and resize it.
5. Tap the check mark or back arrow to save, and share the file from the menu.

Acrobat may ask you to sign in with an Adobe, Google or Apple account to save signatures. Its button positions change between app versions, but the “Fill & Sign” name has stayed the same. It doesn't record who signed or when.

3. Google Drive (sign by hand)

Most Android phones already have Google Drive. Recent versions of its PDF viewer let you write on a PDF with a pen tool.

1. Open the PDF in the Drive app (upload it first if it's not there).
2. Tap the annotate button at the bottom right (it needs Android 6.0 or later; update the Drive app if you don’t see it).
3. Pick a pen and sign with your finger where the signature goes.
4. Save over the original or as a new copy, then download or share it from the menu.

It works in a pinch, but signing freehand with a finger at page size rarely looks neat, and there's no saved signature to reuse.

What about Samsung phones?

Samsung Galaxy phones often include Samsung Notes, which can import a PDF and let you write on it with a finger or S Pen, then export it as a PDF again. It's handy if you already use an S Pen. The menus differ by model and One UI version, so if you can't find the option, the browser method above works the same on every Samsung.

Sign a paper document on Android

To sign something you only have on paper, scan it first. In the Google Drive app, tap “+” and choose “Scan,” or use your phone's camera app if it offers document scanning. Save the scan as a PDF and sign it with any method above. Or skip the step: upload a photo straight to MultiDocs, which straightens it and makes it look scanned.

Get someone else to sign from Android

None of the built-in tools can ask another person to sign. With MultiDocs you can, from the same page in Chrome:

1. Upload the document and choose “Other people” (or “Others and me” if you sign as well).
2. Tap “Mark where they sign” and place the box. Add fields for their name, date or initials.
3. Enter their email or mobile number. With text or WhatsApp, your phone opens the message ready to send from your own number; there's no SMS fee from us. Or copy the link.

They sign in their browser without an account, and you get the signed PDF by email with its audit trail. Free plan: 15 requests a month, up to 20 signers per document. See send for signature by text.

Which way is best?

Is it legally binding?

Yes. Under the federal ESIGN Act, a signature or contract “may not be denied legal effect, validity, or enforceability solely because it is in electronic form” (15 U.S.C. § 7001(a)), and an electronic signature can be any “sound, symbol, or process” adopted with the intent to sign (§ 7006(5)). A finger-drawn signature on Android qualifies. If the signature might be disputed, the audit trail is what proves who signed. Exceptions such as wills are listed in documents that can't be e-signed.