How to Sign a PDF on iPhone, Android and Computer (Without Printing)

A lease, a supplier contract, a school authorization, an invoice that needs a signature before payment. The document arrives as a PDF, and the office wants it back today. Printing, signing, scanning and sending a photo of the page works, but it is slow and the result often looks worse than the original.

Signing the PDF directly is faster. You draw or type a signature, place it on the right page, adjust the size and download the file. On a phone, it takes a couple of minutes once you know where the buttons are.

There is one thing to settle first: a signature placed on a PDF is not automatically a qualified electronic signature. It is a visual signature added to the document. For many everyday uses that is enough; for others, it is not, and no tool can decide that for you.

What this signature can and cannot do

OpenToola writes a signature image into the PDF. The result looks like a signed document, and most recipients will treat it as one. It is a simple electronic signature in the broad sense: a mark associated with a person and a document.

It is not a cryptographic signature. It does not use a certificate, it does not prove that the file was unchanged after signing, and it does not create a qualified electronic signature under eIDAS in the EU or an equivalent framework elsewhere. If a bank, a court, a notary or a government portal asks for a certified or qualified signature, use the provider or the portal they specify. A drawn signature will not pass that check.

For everyday contracts and forms, a simple signature is often accepted. Ask the recipient what they require before choosing a tool.

Sign on a computer

Open the Sign PDF tool in your browser. Select the PDF. The first page appears in the preview.

Choose how you want to create the signature. You can draw it with a mouse, a trackpad or a stylus, or type your name and use the typed version. A drawn signature usually looks more natural, but a typed one is easier to read. Avoid using a photo of your signature on a white sheet: the white rectangle can cover the text underneath and looks pasted on.

Once the signature is ready, place it on the page. Drag it to the signature line. Use the size slider to make it proportionate. A signature that spans a third of the page looks like a stamp; one that is too small looks like a smudge. Somewhere between a quarter and a third of the page width is a good starting point.

If the document has several pages, use the page navigation to move through them. Place the signature on each page that requires one. The tool keeps the placements while you move around, then writes them into the PDF when you download.

Download the file and open it in a PDF reader. Check the position at normal zoom and at 100 %. A signature that looks fine in the thumbnail can sit over a line of text when the page is opened at real size.

Sign on iPhone

On iPhone, save the PDF to Files first. Open the Sign PDF tool in Safari, tap the file picker and choose the document. The preview may take a moment to render.

Draw the signature with a finger. It will not be as precise as a stylus, but it is usually enough. If the signature looks shaky, clear it and try again with slower strokes; speed is what makes it look messy. Typing the name is a clean alternative when the signature does not need to match a previous one.

Place the signature, then use two fingers or the size slider to adjust it. Move the page preview if the signature line is near the bottom. On a small screen, zoom in before positioning; it is easier to see whether the signature sits above the line or crosses it.

When you download, the file may open in a new tab. Use the share button and choose Save to Files. Rename it so you can find it later: lease-signed-2026.pdf is better than document.pdf.

If the PDF is in Mail or WhatsApp, save it to Files first; the picker does not always show attachments stored inside another app.

Sign on Android

The steps are the same in Chrome. Open the PDF, draw or type the signature, place it, download. Android file pickers vary by manufacturer; if the PDF is in Downloads, use the Downloads section, and if it is in Drive, choose Drive.

Stylus support depends on the phone and the browser. A Samsung phone with an S Pen produces a cleaner signature than a finger, but a finger is fine. Android sometimes opens the downloaded PDF in a viewer instead of saving it where you expect; use the share menu to send it or save it to Files first. Check that the signature is visible in the final file, not just in the preview.

Place it so nobody has to guess

The signature should sit on the signature line, not beside it. If there is a date line, add the date in the document if the form allows it, or write it clearly near the signature. Do not cover the printed name, the title or the small print with a large signature image.

Initials matter on contracts. If the document has initial boxes on each page, sign or initial each one. A signature on the last page only can be rejected when the contract requires every page to be initialled.

If the PDF already contains a signature image, do not place yours on top of it. That looks like an alteration. Add a new page if the document needs a second signatory, or ask the sender for a version with the correct fields.

Multiple pages, dates and stamps

Sign where the document asks: the last page, an approval block, a specific clause. Initial the pages that have an initial box. If you are unsure, sign the last page.

A date is part of the signature for many documents. Write it in the format used by the recipient: day/month/year in much of the world, month/day/year in the United States. If the document has a printed date field, fill it by hand or with a text tool before signing, not after.

The legal part, without the fairy tale

A simple electronic signature is accepted for many commercial documents, but the details depend on the jurisdiction and the type of act. In the EU, eIDAS distinguishes simple, advanced and qualified electronic signatures. In the United States, ESIGN and UETA give electronic signatures broad validity, with exceptions such as wills, some family law documents and certain notices. Other countries have their own rules.

A qualified signature requires a certificate and a trusted creation device, usually from a qualified trust service provider. It is the right tool when the law demands it; a drawn signature in a browser is not a substitute. Some public services require you to sign inside their portal, using an account or a digital identity. In that case, the PDF you sign elsewhere may be rejected even if the signature is genuine.

If you send a contract, say in the email that you signed the PDF and ask whether a certified signature is required.

Mistakes that get documents rejected

The usual mistakes are signing the wrong page, a signature that is too large or covers text, and a low-resolution signature that prints badly.

A signature image with a white background can hide the line underneath. Use a transparent signature or draw directly in the tool.

Sending a PDF that still has a password, or a file that was compressed until the text is unreadable, also causes rejections. Remove the password before signing, and compress only after checking the result.

When the file refuses

A password-protected PDF cannot be opened for signing until it is unlocked. Remove the password in the app that created it, then try again.

A very large PDF may be slow to render on a phone. Close other tabs or use a computer. If the preview loads but the signature does not appear in the downloaded file, try a different browser and check that you actually placed the signature before downloading.

If the recipient says the signature is invisible, ask them to open the file in a different reader. Some viewers render image overlays differently, especially old versions. A flattened copy may be needed for very old systems.

What stays on your device

The PDF and the signature are processed in the browser. OpenToola does not upload them and does not keep an account with your signed documents. When you close the tab, the working copy is gone unless you downloaded it.

That does not make a shared computer safe. Delete the downloaded file after sending it, avoid signing on a public machine if the document is sensitive, and keep your browser and system updated. A local tool removes the upload risk; it does not remove every risk.

Tools mentioned

• Sign PDF
• Merge PDF
• Compress PDF
• OpenToola Guides