Save the PDF where you can open it
A PDF attached to an email or a chat message is not always reachable by other apps until you save it. On iPhone, open the attachment, tap share and choose Save to Files. On Android, download the attachment so it appears in your Downloads folder. Either way, you now have a file a browser can pick up.
Read the document before signing it — on a phone it is easy to scroll past the terms to the signature line. Zoom in on anything you are agreeing to, and check whether the document asks for more than a signature: a printed name, a date, initials on each page or a witness. Knowing that up front avoids signing an incomplete form.
Note where every signature is required. Multi-page agreements frequently need initials on several pages and a full signature on the last. Make a quick list of page numbers so you do not finish signing and discover a page you missed.
Sign it in your phone’s browser
Open Sign PDF in Safari or Chrome and select the document from Files or Downloads. You can create your signature in three ways: draw it with your finger, type your name and pick a handwriting-style font, or upload an image of your real signature.
The signing happens entirely in your phone’s browser. Neither the document nor your signature is uploaded to a server, which matters when the document is a tenancy agreement, an employment contract or a medical consent form, and when the thing being handled is a copy of your signature.
Choose the method that matches how the signature will be judged. A typed signature is tidy and legible, which suits routine approvals. A drawn signature looks most like a real one. An uploaded image of your paper signature gives the most consistent result across many documents — useful if you sign things on your phone regularly.
Draw a signature that looks like yours
Turn the phone sideways before drawing. Landscape gives you a wider pad, which lets you sign at a natural speed instead of cramming a full signature into a narrow strip. Most people’s phone signatures look wrong because they were drawn too small and too slowly.
Sign with one confident stroke, the way you would with a pen, rather than carefully tracing letters. If the first attempt looks shaky, clear it and try again — it usually takes two or three goes to get one you are happy with. A stylus helps if you have one, but a fingertip is perfectly adequate.
For a signature you can reuse, sign a piece of white paper in dark ink, photograph it in good light and crop it tightly. Save that image on your phone and upload it whenever you need it. The tool does not store your signature between visits, so keeping your own image is the way to get the same signature every time.
Place it on the right line and page
Go to the page with the signature line and place your signature on it, then size it so it sits on the line at roughly the scale of a handwritten signature. Too large and it overlaps the printed text around it; too small and it looks like an initial. Zoom in while positioning — accuracy is much easier at magnification.
Repeat for every page on your list. For initials on several pages, a small typed or drawn set of initials positioned consistently in the same corner looks deliberate and makes it easy for the recipient to confirm that every page was seen.
If the document also asks for a printed name or a date next to the signature, add those as text with Edit PDF. The guide to filling out a PDF form covers adding text neatly to the boxes on a document that was not designed to be filled on screen.
Use the built-in tools when they fit
iPhone and iPad include markup tools in the Files app, with an option to add a signature to a PDF. They are convenient for a quick signature on a simple document, and they save the result in Files. Many Android phones include a similar markup option in their built-in PDF viewer or file manager, though the feature and its wording vary by manufacturer.
The built-in tools are perfectly good for occasional use. A browser tool is more useful when you want the same steps on any phone, when you want to type or upload a signature rather than only drawing one, or when the device’s own viewer does not offer signing at all.
Formal agreements may need something different entirely. Some contracts must be signed through a certified e-signature service that verifies identity and records an audit trail, and a few documents still require a wet signature on paper. If the sender specifies a method, use that method.
Check, save and send the signed copy
Download the signed PDF and open it from Files or Downloads to confirm the signature appears on every page where it should, in the right position, and that nothing on the page was covered. Opening the saved file, rather than trusting the preview, proves the signature was actually written into it.
Rename the signed file so it is obviously the signed version — the original name with “signed” and the date works well. Send that file using the share action from Files or Downloads, which avoids accidentally attaching the unsigned original still sitting in your mail app.
Keep a copy of what you signed. On a phone, signed documents disappear quickly into a downloads folder, and you may need to show exactly what you agreed to later. The desktop signing guide covers the same steps if you later need to sign from a computer.
Open Sign PDFDraw with your finger, type or upload — works in your phone’s browser.
Open Sign PDF →Frequently asked questions
Is a signature drawn on a phone legally valid?
For many everyday documents a drawn electronic signature is accepted, but rules vary by country and document type. Some agreements require a certified e-signature service or a wet signature, so check with the recipient.
Is my signature uploaded anywhere?
No. PDFNest’s Sign PDF runs in your phone’s browser, so the document and your signature stay on the device.
Can I reuse the same signature next time?
The tool does not store your signature. Save a cropped photo or PNG of your signature on your phone and upload it each time for a consistent result.