Do I need an app to sign a PDF on iPhone?

No. This page works in Safari, and your iPhone also has a built-in Add Signature option in Markup. Use whichever is easier for you.

Where is the signed PDF saved on my iPhone?

Unless you have changed Safari's download location, it is in the Downloads folder in the Files app, named after the original with -signed at the end. The original PDF is not changed.

My finger signature looks shaky. What can I do?

Draw it large across the whole box, then make it smaller on the page with the corner handle. Or tap Type and choose a handwriting font.

Is this a legally binding digital signature?

It adds a picture of your signature, not a certificate-based digital signature. Whether that is enough depends on the document and on who asked for it.

Sign PDF on iPhone – Draw Your Signature with a Finger, Free

How to sign a PDF on iPhone

Draw your signature in the box with one finger. The page doesn't scroll while you draw. Tap Undo or Clear to try again, or tap Type to use your typed name in a handwriting font.
Tap Choose PDF. Your iPhone shows the Files picker, so a PDF you saved from Mail or Safari is usually in Downloads or On My iPhone.
If the PDF has several pages, pick the page under Page … of …. The signature starts near the lower right of the page.
Drag the signature with your finger to move it, and drag the round handle at its corner to make it bigger or smaller.
Tap Download signed PDF. The copy is called name-signed.pdf; the original isn't changed. Unless you've changed Safari's download location, it's in the Downloads folder in the Files app.

A wavy test signature drawn by touch in the signature box — Test signature drawn with touch input in iPhone 13 emulation, October 22, 2026.

The signature placed on page 1 of an invoice in a phone-sized browser, with a dashed frame and a round resize handle, above the Download signed PDF button — The same signature dragged up the page and enlarged with the corner handle, both by touch.

What we found when we tested it

We ran the live tool on October 22, 2026 (PT) in Google Chrome 155 on Linux, with sample files we made for the test. All of our phone tests used Chrome's iPhone 13 device emulation with real touch events (and Pixel 7 for Android). Our test machine can't run Safari or Apple's WebKit engine, so we have not tested on a real iPhone. Treat these results as a strong hint, not proof. We signed page 1 of a 3-page invoice (8,609 bytes).

Check	Result
Drawing with a finger	The stroke appeared in the box and the page stayed still: the scroll position was the same before and after drawing.
Transparent PNG	Download transparent PNG worked after drawing and saved `signature.png`.
Moving the signature	Dragged by touch from the lower right to the upper middle of the page. In the downloaded PDF the signature was in the new place.
Resizing	Dragging the corner handle made the signature box about 1.6 times wider (from 92 to 146 pixels on screen) and kept its proportions. The signature in the PDF was larger to match.
Downloaded file	`s5-invoice-3p-signed.pdf`, 24,178 bytes, still 3 pages. Text on the page could still be selected.
Certificate signature	None: `pdfsig` found no signatures. It's an image, not a digital signature.
Android	The same steps worked in Pixel 7 emulation (22,098-byte signed file).

Your iPhone can sign PDFs too

You don't need a website for this. Apple's iPhone User Guide describes opening the document (in the Files app if prompted), tapping the Markup button, then Add Signature: you sign with your finger, tap Done and drag the signature where it should go. You can resize it by dragging the blue dots, and your iPhone saves the signature for next time. Apple's Preview app on iPhone has its own guide for filling out and signing PDF forms.

This page is useful when you want a typed signature in a handwriting font, a transparent PNG of your signature to reuse elsewhere, or when you're signing on a phone you don't want to save a signature on: nothing is kept after you close the tab.

Tips for a neater finger signature

Draw it large across the whole box, then shrink it on the page with the corner handle. Small finger signatures look shaky.
Turn your iPhone sideways if you want a wider box to draw in.
Pick Navy or Blue ink if the person who asked wants to see that it was signed rather than printed.

Know what this signature is

It's a simple electronic signature: a picture on the page, with no signing certificate or tamper seal.
If someone sent you a link from an e-signature service, sign there instead; they usually need their own record.
One signature per download. To sign several pages, download, choose the signed file again and add the next one.
It doesn't fill in form fields or add dates or text.

Privacy

The work happens in your browser tab, so your files aren't uploaded. The site counts page visits and sends one anonymous event per use (tool name, whether it worked, a file-size range). No event is sent when Global Privacy Control or Do Not Track is on. See the privacy policy.

Related tools

Sign PDF: the main tool
Sign PDF on Mac
Merge PDFs on iPhone
Photo to PDF on iPhone
Compress PDF to 2MB: if the signed file is too big to send

Sources

Apple iPhone User Guide, "Fill out forms, sign documents, and create signatures on iPhone": https://support.apple.com/guide/iphone/fill-forms-sign-documents-create-signatures-iph1d3607e5c/ios
Apple iPhone User Guide, "Fill out and sign PDF forms in Preview on iPhone": https://support.apple.com/guide/iphone/fill-out-and-sign-pdf-forms-iphd7e3c0c74/ios
Apple iPhone User Guide, "Find your downloaded files on iPhone": https://support.apple.com/guide/iphone/find-your-downloaded-files-on-iphone-iphc9cd7266c/ios
PDFWrangle Sign PDF, live tool, checked October 22, 2026: https://pdfwrangle.com/sign-pdf

Sign a PDF on iPhone