Add text notes, highlights, and freehand drawings to a PDF in your browser, then save with the marks flattened into the pages. Original content stays intact and selectable — no upload, no signup.
Text, Highlight & Freehand Ink Flattened Into the Page Original Pages Preserved 100% Client-Side
Last updated
Annotate PDF — Add Text & Highlights is a free, browser-based tool
from UseToolSuite's
Document & PDF Tools collection.
All processing happens locally on your device — your data is never uploaded to any server.
Use the tool below, then scroll down for detailed documentation, frequently asked questions, and related resources.
Advertisement
Drop a PDF here or click to select
Add text, highlights, and drawings — nothing is uploaded
100% private Original pages kept Works offline
Click on the page to place text
1 / 1
About the PDF Annotator
This tool adds text notes, highlights, and freehand drawings to any PDF — the everyday "edit a PDF" tasks: filling a label onto a flat form, highlighting clauses in a contract, marking corrections on a draft, or circling something in a report. Your original pages are kept fully intact (no rasterization — the text underneath stays selectable), and your annotations are drawn permanently into the page content when you save, so they appear identically in every viewer and can't be silently removed like detachable comment objects. Everything runs in your browser with pdf.js and pdf-lib; the document is never uploaded.
How to Annotate a PDF
Drop in your PDF — the first page renders as a live canvas.
Pick a mode — Text (click to place a note), Highlight (drag over a region), or Draw (freehand ink).
Set color and text size from the toolbar; navigate pages with the arrows.
Undo or remove any annotation from the chips below the canvas.
Save — annotations are flattened into the PDF and it downloads immediately.
Annotating vs. editing original text
An annotator adds a layer on top of the page — it doesn't rewrite the PDF's existing text, because in a PDF the original characters are placed at fixed coordinates with embedded fonts, and true in-place editing reliably requires the source document. If you need to change the underlying text, convert the file with PDF to Word, edit it there, and export back to PDF. For a signature specifically, the Sign PDF tool places a drawn or typed signature; and to permanently black out sensitive content, use Redact PDF rather than a highlight.
Annotation is a layer model — use it like one
Everything this tool adds sits on top of the existing page, which is exactly the right mental model for the tasks it serves: filling a value onto a flat form that has no fields, marking a correction on a draft, highlighting the clause that matters, circling the number that’s wrong. The page underneath — vector text, embedded images, fonts — is copied into the output untouched, so nothing loses sharpness and the original text stays selectable beneath your marks.
That layer model also tells you when to reach for a different tool. If the form has real, clickable fields, the PDF Form Filler writes into them properly instead of painting text on top. If the mark you need is a signature, the Sign PDF tool handles drawn and typed signatures with placement built for that job. And if your goal is to hide content rather than add it, a highlight or a drawn box is the wrong instrument entirely — an opaque rectangle over text leaves the text present and extractable underneath. Use Redact PDF, which removes the content itself.
Why flattening on save is the safe default
This tool bakes your marks into the page content at save time rather than storing them as comment objects, and that choice is deliberate. Comment-style annotations depend on viewer support: they can be hidden with one click, silently dropped by some mobile viewers and print pipelines, and stripped by document-processing systems. For the use cases above — a form value, a permanent note, a correction — you want the mark to be as durable as the document. Flattened content is exactly that: it renders everywhere the page renders, prints every time, and can’t be peeled off without editing the page itself.
How to Use This Tool
1
Upload your PDF
The first page renders as a live, zoom-fit canvas.
2
Pick a mode
Text: click to place a note. Highlight: drag over a region. Draw: freehand ink. Set color and text size from the toolbar.
3
Review and adjust
Navigate pages with the arrows; remove any annotation from the chips under the canvas, or Undo the last one.
4
Save
Annotations are drawn permanently into the page content and the PDF downloads.
How helpful was this tool?
Click to rate
Awesome! Glad it helped.
We don't have a marketing budget. The best way to support this free tool is by sharing it with other developers!
Help us improve!
Sorry it didn't meet your expectations. We're always looking to make these tools better. What was missing or broken?
Essential terms and definitions related to Annotate PDF — Add Text & Highlights.
Flattening
Merging annotations into the page's actual drawing instructions instead of storing them as separate, removable annotation objects. Flattened marks render identically everywhere and survive printing, re-saving, and viewers that ignore comment layers.
Frequently Asked Questions
Can I edit the PDF's existing text with this tool?
No — and no browser tool honestly can, reliably. A PDF stores its original characters at fixed coordinates with embedded fonts; rewriting them in place requires reconstructing the layout. This tool adds a layer on top: text notes, highlights, and drawings. To change the underlying text, convert the file with PDF to Word, edit it there, and export back to PDF.
Will my annotations show up in every PDF viewer?
Yes. When you save, the annotations are drawn directly into each page's content stream (flattened) rather than stored as detachable comment objects. That means they render identically in every viewer and print exactly as shown — and they can't be silently toggled off or deleted the way sticky-note style annotations can.
Does annotating rasterize my document or blur the text?
No. The original pages are kept as-is — vector text, images, and fonts are untouched, and the underlying text remains selectable. Only your added marks are drawn on top. The file stays sharp at any zoom level because nothing is converted to an image.
Is the PDF uploaded anywhere?
No. Rendering (pdf.js) and saving (pdf-lib) both run in your browser; the document never leaves your device. You can confirm it in the Network tab — no file upload occurs — and the tool works offline once the page is loaded.
What's the difference between flattened annotations and PDF comments?
PDF comments (sticky notes, review highlights) are separate annotation objects that sit alongside the page — viewers can show, hide, edit, or strip them, and some viewers don't render them at all. Flattened annotations are drawn into the page's own content, so they behave like ink on paper: identical in every viewer, always printed, and not removable through a comments panel. Use comment-style markup for collaborative review rounds; use flattening when the marks are part of the final document — a filled label, a permanent note, a highlight that must survive.
Why can't a browser tool edit the text that's already in my PDF?
Because a PDF stores its text as positioned glyphs — characters placed at fixed coordinates using embedded font subsets — not as a flowing document. Changing one word means re-laying-out the line (and possibly the paragraph and page) with font data that often isn't fully embedded. Desktop editors approximate this with heuristics and still frequently break layout. The reliable route is converting to an editable format, making the change there, and exporting back to PDF — which is why annotation (adding on top) and editing (changing the source) are genuinely different operations.
Troubleshooting & Technical Tips
Common errors developers encounter and how to resolve them.
My text note appears slightly off from where I clicked
Text is anchored at the click point and flows down line by line. For precise placement, zoom your browser to 100% and click exactly where the first line should start. You can always remove the note from the chips below the canvas and place it again.
Special characters in my note come out as "?" in the saved PDF
The flattened text uses the standard Helvetica font, which covers Western European characters. Characters outside that set (some accented letters, non-Latin scripts) are replaced rather than crashing the export. Keep notes to Latin characters for exact output.
Highlights cover the text instead of looking like a marker
Highlights are drawn semi-transparent (35% opacity) so the text shows through, matching how physical highlighters look. If a region appears too dark, your chosen color may be too saturated — pick a lighter yellow or green.
We use cookies to show personalized ads via Google AdSense.
All our tools process data locally in your browser — no personal data is collected.
You can accept personalized ads or continue with general ads only.
Privacy Policy
