The simplest way to modify a PDF on iPhone

You can mark up, sign, and edit text in PDFs using the built-in tools on your iPhone without downloading anything extra. Open the PDF in the Files app, Mail, or Safari, tap the markup button (it looks like a pen tip in a circle), and you can add notes, draw, highlight, or sign right there. For basic changes — adding your signature, circling something, or writing a note in the margin — this built-in method is faster than installing an app.

If you need to do more than mark up a PDF — like change the actual text, delete pages, or rearrange them — you will need a dedicated app. The built-in tools let you annotate (add marks and notes on top), but not edit the document itself. Understanding the difference between these two things saves you from downloading the wrong tool.

Key Takeaways

  • The iPhone's built-in markup tools let you highlight, draw, add text boxes, and sign PDFs without installing an app.
  • Markup adds notes and marks on top of a PDF but does not change the actual text or structure of the document.
  • To edit text, delete pages, or rearrange a PDF, you need a third-party app like Adobe Acrobat Reader, PDF informed, or Notability.
  • Most PDF editing apps offer a free version with basic features and a paid version for advanced work like form filling or batch processing.

Using iPhone's built-in markup for notes and signatures

Open any PDF on your iPhone — whether it is in Mail, Files, Safari, or another app — and look for the markup icon. On most screens it appears as a pen tip inside a circle, usually in the top right or bottom of the screen. Tap it, and a toolbar appears with five tools: pen (for drawing), highlighter, sketching pen, text box, and signature.

The pen tool works like a ballpoint pen and is best for circling things or drawing arrows. The highlighter is transparent and works like a physical highlighter marker. The sketching pen is thicker and better for freehand notes. The text box lets you type words directly onto the page without handwriting. The signature tool saves your signature so you can add it to any PDF without signing by hand each time.

When you finish marking up the PDF, tap "Done" and then "Save" or "Add to Files." The marked-up version replaces the original, so if you want to keep both versions, duplicate the file first. This approach works well for contracts you need to sign, forms where you just need to check boxes, or documents where you want to add comments without changing the actual content.

Apps for editing text and restructuring PDFs

Adobe Acrobat Reader is free and handles most common tasks: it lets you highlight, add notes, sign, and fill forms. The paid version (Adobe Acrobat Premium) adds the ability to edit text directly, delete or rearrange pages, and compress file size. If you only need to mark up PDFs and sign them, the free version is enough.

PDF informed costs money upfront but gives you full editing power without a subscription. You can edit text, delete pages, merge multiple PDFs, add watermarks, and fill forms. It works offline and syncs with iCloud, so your changes appear on your Mac or iPad too. This is the best choice if you work with PDFs regularly and want to avoid monthly fees.

Notability is designed for note-taking and handwriting but handles PDFs well. You can import a PDF, write notes on it, highlight, and export it back as a PDF. It is popular with students and people who prefer writing by hand. It costs money but includes unlimited cloud storage and works across iPhone, iPad, and Mac.

GoodNotes 5 is similar to Notability — it is built for handwritten notes but works with PDFs. You can import a PDF, annotate it by hand, and export it. Like Notability, it costs money and syncs across Apple devices. The choice between Notability and GoodNotes comes down to which interface you prefer; both do the same core job.

Filling out forms and signing documents

If the PDF is a form with fields (like a tax document or process), most PDF apps will recognize those fields and let you type directly into them instead of handwriting. Open the PDF in Adobe Acrobat Reader, PDF informed, or the built-in markup tool, and tap on a field to type. This is much cleaner than handwriting and easier to read.

For signing, use the signature tool in the markup menu or in your chosen app. Most apps let you create a signature once and reuse it on every document. Some apps also let you import a photo of your signature if you prefer that look. Once you sign, export the PDF and send it — most recipients will accept a digitally signed PDF just as they would a printed and scanned one.

Choosing between free and paid apps

If you mark up a PDF once a month or less, the built-in markup tool and free Adobe Acrobat Reader cover everything you need. You will never hit a paywall, and you will not waste storage on an app you barely use.

If you work with PDFs several times a week — editing text, rearranging pages, or filling complex forms — a paid app like PDF informed or Notability pays for itself in time saved. These apps are faster to navigate, have better search, and let you batch-process multiple PDFs at once. The cost is usually between $10 and $30 one time, or $5 to $10 per month for a subscription.

Some apps offer a middle ground: free with limited features, and a paid upgrade for advanced work. Adobe Acrobat Reader is the most common example. Try the free version first, and only pay if you hit a feature you actually need.

Exporting and sharing your edited PDF

After you finish editing, you need to save the file in a format the recipient can open. Most apps export as PDF by default, which is what you want. Tap "Export," "Share," or "Save," choose PDF as the format, and select where to send it — email, Messages, Files, or cloud storage like iCloud Drive or Google Drive.

If you are sending a marked-up PDF to someone else, they will see all your notes, highlights, and signatures. If you want to remove your annotations before sharing, most apps have a "flatten" or "merge annotations" option that bakes your marks into the PDF so they cannot be edited separately. Check your app's export menu to see what options are available.

Frequently Asked Questions

Can I edit the actual text in a PDF using only the built-in iPhone tools?

No. The built-in markup tool only lets you add notes, highlights, and drawings on top of the PDF. To change the text itself, delete pages, or rearrange content, you need a third-party app like Adobe Acrobat Premium or PDF informed.

Do I need to pay for an app to mark up and sign PDFs?

No. The built-in markup tool is free and handles marking up, highlighting, and signing. Adobe Acrobat Reader is also free for basic markup. You only need to pay if you want advanced features like text editing or page rearrangement.

Will my signature on a digital PDF be legally valid?

In most cases, yes. A digital signature on a PDF is legally binding in the United States and most countries, as long as both parties agreed to sign electronically. However, some documents (like wills or real estate deeds) may have specific legal requirements. Check with the organization asking you to sign if you are unsure.

Can I edit a PDF that is password-protected?

If the PDF is locked to prevent editing, you will not be able to change it without the password. If you have the password, enter it when the app asks. If you do not have it, you will need to contact whoever created the PDF and ask them to unlock it.

What is the difference between marking up and editing a PDF?

Marking up means adding notes, highlights, and drawings on top of the existing content without changing the original text or structure. Editing means changing the actual text, deleting pages, or rearranging the document. Markup is non-destructive; editing changes the document itself.