How to Annotate a PDF for Free (2026 Guide)

Whether you're reviewing a contract, marking up a study reading, or sending feedback on a draft, annotating a PDF lets you layer comments, marks, and drawings on top of a document without ever touching the underlying text. This guide covers every annotation type and when to reach for each, the exact steps from upload to download, and the snags people hit — like annotations that won't stick to a scanned page or look wrong in someone else's reader.

Annotation vs. Editing: Why the Difference Matters

Annotating and editing are not the same thing, and confusing them causes most of the frustration people have with PDFs. Editing changes the actual content — rewriting a sentence, deleting a paragraph, swapping an image. Annotating leaves the original content exactly as it is and adds a separate layer of marks on top: a highlight, a comment, an arrow. That distinction is what makes annotation safe for documents you don't own or shouldn't alter, like a signed agreement or a published paper — you're recording your reaction to the document, not rewriting it.

The Annotation Types — and When to Use Each

Most tools bundle several markup tools together. Picking the right one for the job keeps your markup readable for whoever opens the file next:

Highlight — best for flagging passages you want to return to or call attention to. For a deep dive on color and scanned-text highlighting, see our dedicated guide to highlighting a PDF.
Underline — a lighter-touch emphasis than a highlight; useful when a full color band would clutter dense text.
Strikethrough — signals "remove this" or "this is outdated" during a review, without actually deleting anything.
Text notes & comments — attach a written explanation to a specific spot. This is where the real feedback lives: "clarify the refund window here."
Sticky notes — collapsible comment markers that keep long remarks tucked away until the reader clicks them, so the page stays clean.
Freehand drawing — circle a figure, sketch a correction, or jot a quick mark with a stylus or trackpad.
Shapes & arrows — point to an element, box a region, or connect a comment to the thing it refers to.

If you find yourself wanting to type a full sentence into the document itself rather than as a note, that's a job for adding text to a PDF instead.

How to Annotate a PDF: Step-by-Step

Step 1: Upload your PDF

Open EditPDFs.app and drop in the file you want to mark up. The document opens in the viewer with a markup toolbar, and your pages render exactly as they'll look when you export — nothing is altered yet.

Step 2: Pick the right tool

Choose a tool from the toolbar — highlighter, note, drawing pen, shape, and so on. Most tools let you set a color before you start, which is worth doing up front so you're not recoloring marks afterward.

Step 3: Apply your marks

For text-based marks like highlight or underline, drag across the words. For notes, click where you want the marker and type. For drawings and shapes, click-drag to place them. You can move, resize, or delete any annotation before exporting, so don't worry about getting placement perfect on the first pass.

Step 4: Download the annotated PDF

Export the file. Your annotations are written into the PDF as standard markup, so they show up in Acrobat, Preview, Chrome, and every other mainstream reader. The original document content underneath is unchanged.

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Getting Annotations Right: A Few Habits

Annotation is only useful if the next person can decode it. A consistent color key goes a long way — for example, yellow for "important," red for "problem," green for "approved" — and it's worth stating that key in a note on the first page when you share with a team.

Be specific in comments: "update this date to 2026" is actionable in a way that "fix" never is. And resist the urge to mark everything — if half the page is highlighted, nothing stands out. Selective markup is what makes the important bits visible.

Troubleshooting Common Problems

My annotations didn't save in the downloaded file

Make sure you exported a new copy after marking up rather than re-downloading the original. If you closed the tab before exporting, the marks aren't stored anywhere — annotation happens in your browser, so always download before you leave the page.

I can't highlight text on a scanned PDF

A scanned page is an image, so there's no selectable text to grab. You can still annotate it — use the freehand pen, shapes, or sticky notes placed on top of the image. If you need true text highlighting, run the file through OCR first to make the PDF searchable, then highlight as normal.

The PDF is secured and won't let me annotate

Some files carry a permissions password that blocks markup. If it's your document and you know the password, you can remove the password first, then annotate the unlocked copy.

My annotations look different in another app

Readers render markup slightly differently, and a few older viewers hide comments behind an icon you have to click. If you need the marks to appear identically everywhere — say, before printing — flatten the file so annotations become part of the page. See how to flatten a PDF.

How do I remove an annotation?

Before exporting, select the mark and delete it. After exporting, re-upload the file and delete the markup there — unless it was flattened, in which case it's baked into the page and can't be lifted back out.

Annotating on Specific Devices

Windows / Mac (any browser): The steps above work the same on both — no install required. A mouse is fine for highlighting and notes; a trackpad handles freehand drawing in a pinch.
iPhone / iPad: Open EditPDFs.app in Safari and mark up by touch. An Apple Pencil makes freehand annotation genuinely comfortable on iPad.
Android: Use Chrome the same way — upload, annotate by tapping and dragging, then download the marked-up copy to your device.

Who Annotates PDFs, and How

Students & researchers highlight key findings and drop notes in the margin while reading papers, building a marked-up library they can skim later.
Contract reviewers strike through outdated clauses and attach comments asking for changes — without editing the legal text itself.
Teams giving feedback use color-coded highlights and sticky notes so several reviewers' comments stay distinguishable on one shared file.

A Note on Privacy

Plenty of annotation sites upload your document to their servers to process it — not ideal when you're marking up a contract or anything confidential. On EditPDFs.app, the whole process runs in your browser, so the file you're annotating never leaves your device.

Frequently Asked Questions

Is annotating a PDF free?

Yes. On EditPDFs.app it's completely free with no signup, no watermark, and no limit on how many files you mark up.

Does annotating change the original document?

No. Annotations sit in a separate layer on top of the page, so the underlying text, images, and layout stay exactly as they were. That's the whole point of annotating instead of editing.

Will the people I share with see my annotations?

Yes. The marks are embedded in the file you download, so anyone who opens it in a standard reader sees them. A few older viewers tuck comments behind a clickable icon rather than showing them inline.

Can I annotate a scanned PDF?

You can add drawings, shapes, and sticky notes on top of a scan right away. To highlight or underline actual words, run OCR first to make the text selectable.

How do I make annotations permanent?

Flatten the PDF after annotating. Flattening merges the markup into the page so it can't be moved or deleted and looks identical in every viewer — handy right before printing or archiving.

Can multiple people annotate the same PDF?

Yes, by passing the file along — each reviewer adds their marks and re-shares. Using a different highlight color per person keeps everyone's comments easy to tell apart.

Are my files uploaded to a server?

Not on EditPDFs.app. All annotating happens locally in your browser, so the document never leaves your device — which matters when the thing you're marking up is sensitive.