The fastest way to edit a PDF on a Mac is Preview, the app already built into your system

You do not need to buy software or read anything. Open the PDF in Preview (the default when you double-click a PDF file), click the markup toolbar icon in the top right, and you can add text, draw, highlight, or sign directly on the page. Preview saves your changes to the original file unless you choose File > Export As to keep a separate version.

Preview handles the most common edits: adding your signature, highlighting passages, crossing out text, drawing boxes or arrows, and typing new text into blank spaces. It works for forms, contracts, meeting notes, and any PDF where you need to mark it up or add information. If you need to do something more complex — like rearranging pages, merging multiple PDFs, or changing the actual text that was printed into the document — you will need a different tool.

Key Takeaways

  • Preview is built into every Mac and can highlight, annotate, sign, and add text to PDFs without opening a separate app.
  • Changes in Preview save directly to your PDF file, so use File > Export As if you want to keep the original unchanged.
  • Preview cannot edit text that was printed into the PDF — it can only add marks on top of the page.
  • For tasks like merging PDFs, rearranging pages, or editing printed text, you will need a dedicated PDF tool like Adobe Acrobat or a free alternative.
  • Keyboard shortcuts in Preview (Command+A for annotation, Command+Shift+A for signature) speed up repeated edits.

How to open the markup tools in Preview

Open your PDF in Preview. In the top right corner of the window, you will see a toolbar icon that looks like a pen tip in a circle. Click it. A row of tools appears below: a pen for drawing, a highlighter, a text box, a signature tool, a magnifying glass, and a few others depending on your macOS version.

Each tool works the same way: select it, then click or drag on the PDF page where you want to add the mark. The pen draws freehand lines. The highlighter adds a transparent colored overlay. The text tool creates a box where you can type. The signature tool lets you sign with your trackpad or add a saved signature from your iPhone.

To change the color or thickness of a line, right-click the tool icon and choose your settings, or look for a color or size menu that appears when you select the tool. Preview remembers your last choice, so if you set the highlighter to yellow, it stays yellow until you change it.

Adding text and signatures to forms

Click the text tool (the capital A icon), then click on the blank space where you want to type. A text box appears. Type your information — your name, date, address, or whatever the form needs. The text appears in the font and size Preview uses by default, which you cannot change within Preview itself.

For signatures, click the signature tool. If you have already saved a signature from your iPhone using the Markup tools on iOS, it appears as an option. Otherwise, you can draw your signature on the trackpad right then. Preview will remember it for future PDFs. If your signature does not look right, click the tool again and redraw it — the new version replaces the old one.

After you add text or a signature, click elsewhere on the page to finish editing that element. You can move it by clicking and dragging, or delete it by clicking it and pressing Delete.

Highlighting, underlining, and crossing out text

The highlighter tool adds a colored transparent layer over text without covering it completely. Click the highlighter, choose your color (yellow is the default), then drag across the text you want to mark. You can highlight the same passage multiple times with different colors if you need to categorize information.

To underline or strike through text, use the pen tool with a thin line weight. Draw underneath the text for an underline, or draw through it for a strikethrough. This is less precise than a dedicated underline tool, but it works for quick marks. If your Mac is running a recent version of macOS, the markup menu may include dedicated underline and strikethrough buttons — check the toolbar to see what your version offers.

All of these marks stay on top of the PDF text. They do not change the actual text underneath, so if someone opens the PDF on another computer, they will see your marks layered over the original document.

Saving your changes and keeping the original

Preview saves your edits to the PDF file automatically as you work. If you close the file and reopen it, your marks are still there. This is convenient if you are the only person editing the file, but it means the original is gone unless you made a backup.

To keep both a marked-up version and an unchanged original, go to File > Export As before you make any edits. Choose a new filename (like "Form_marked.pdf") and save it. Then open the original again and make your edits there. Now you have two files: the original and your annotated copy.

Alternatively, after you finish editing, use File > Export As to save the marked-up version with a new name. This leaves your original unchanged if you had already saved it.

What Preview cannot do, and when you need a different tool

Preview can mark up a PDF, but it cannot edit the text that was printed into the document. If a PDF contains actual text (not just an image of a page), you might think you could edit it, but Preview does not have that ability. You can only add new marks on top.

Preview also cannot merge multiple PDFs into one file, rearrange pages, delete pages, or extract pages from the middle of a document. It cannot compress a PDF to make the file smaller, and it cannot fill in form fields that were created with special form software (though you can add text on top of them).

If you need any of these features, look for a dedicated PDF tool. Adobe Acrobat Pro is the standard but costs money. Free alternatives include PDFtk, Preview's own page-management features in the sidebar (for basic rearranging), or online tools like Smallpdf or ILovePDF. Check what you actually need to do before you read anything — Preview solves most everyday markup tasks.

Keyboard shortcuts that speed up repeated edits

Command+A opens the annotation toolbar (the same as clicking the pen icon). Command+Shift+A opens the signature tool directly. These shortcuts save time if you are marking up many PDFs in a row.

Once a tool is active, you can press the number keys to switch between tools without clicking: 1 for the pen, 2 for the highlighter, 3 for the text tool, and so on. The exact numbers depend on your macOS version and which tools are visible, but Preview shows the number next to each tool icon if you hover over it.

Learning these shortcuts is worth the effort only if you mark up PDFs regularly. For occasional edits, clicking the toolbar is fast enough.

Frequently Asked Questions

Can I edit text that was typed into a PDF form?

Not in Preview. If the form has fillable fields (created with Adobe Acrobat or similar software), Preview treats them as regular text and you can only add marks on top. To edit the actual field content, you need Adobe Acrobat Pro or a free tool that supports form fields, like PDFtk or an online form editor.

What happens if I share a PDF I marked up in Preview with someone else?

They see your marks, your highlights, your text, and your signature all layered on top of the original document. The marks are permanent in that copy of the file. If they need to edit it further, they can open it in Preview and add their own marks, or they can use a different tool to remove your marks if they have the right software.

Can I undo changes after I close a PDF in Preview?

Once you close the file and reopen it, your edits are saved and undo is no longer available. If you made a mistake, you will need to open the original file again (if you kept a backup) or manually remove the marks using the eraser tool in Preview's markup menu.

Does Preview work the same way on iPad?

Yes, but the app is called Markup and it is built into the Files app and Mail. The tools are the same: pen, highlighter, text, and signature. You can even save a signature on your iPad and sync it to your Mac so it appears in Preview.

Can I change the font or size of text I add in Preview?

Preview does not offer font or size options for the text tool. The text appears in a fixed font and size. If you need custom fonts or formatting, you will need to use Adobe Acrobat Pro or export the PDF to a word processor, edit it there, and save it back as a PDF.