How to Highlight and Annotate PDFs in Chrome Without Adobe

Chrome's PDF viewer is decent for basic reading but its annotation support
is minimal. You can't highlight text, add comments, or draw on a PDF without
downloading it and opening it in another application — which breaks your
browsing flow, especially for academic papers and technical reports you
read directly from the web.

Here are the available approaches, from built-in to extended.

What Chrome's built-in PDF viewer can do

• As of 2026, Chrome's PDF viewer supports:
• Text selection and copying
• Fit-to-page and zoom controls
• Text search within the PDF
• A basic drawing tool (via the pencil icon in the toolbar)

• What it can't do natively:
• Text highlighting with persistent color markers
• Sticky comment notes attached to specific text
• Strikethrough or underline annotations
• Saving annotations back into the PDF file

Option 1: PDF.js and Hypothesis

Hypothesis, the web annotation platform, extends to PDFs opened in Chrome.
If you load a PDF from the web (not from your local file system), Hypothesis
can add text-selection-based highlights and comments that persist via their
server.

This works well for academic research where you want annotations stored
cloudside and potentially shareable. Requires a free Hypothesis account.

Option 2: Adobe Acrobat Reader extension

Adobe makes a Chrome extension that replaces Chrome's default PDF viewer.
It supports full annotation: highlights, comments, stamps, drawing. Adobe
requires a free account for basic features, a paid subscription for advanced
ones.

This is the most full-featured option but is heavier and requires going into
Adobe's ecosystem.

Option 3: Sticky Notes Anywhere on PDF pages

Sticky Notes Anywhere works on PDFs opened in Chrome's viewer, but with
a caveat: the notes are positioned as floating overlays on the page, not
embedded in the PDF. This means they don't export with the PDF if you
download a copy.

For the use case of reading a paper and annotating it for your own research,
this is perfectly adequate. Notes persist on that PDF's URL, they appear
every time you open the same PDF, and they integrate with your other browser
annotations.

For PDFs you'll be sharing or need annotations embedded in the file,
you need Option 2 (Adobe) or to download and annotate locally.

Practical setup for research paper reading:

1. Open the PDF from its source URL in Chrome
2. Use Sticky Notes Anywhere (Alt+N) to add floating comment notes
near sections you want to annotate
3. Use Chrome's native text selection to copy quotes you want to
reference — paste these into a research document
4. Use Sticky Notes Anywhere's panel to review all annotations
across all open papers at the end of your session

For local PDFs (opened via file://), the extension functions similarly
but URL matching is based on the file path. If you move the file, the
notes won't be found on the new path.

For critical annotations you need to keep long-term, export your notes
from the Sticky Notes Anywhere panel periodically. The JSON export
preserves the URL, position, and text of each note.

For legal and compliance document review

Lawyers and compliance teams frequently review lengthy regulatory documents,
contract PDFs, and policy filings that don't change once published (they
have permanent URLs). Sticky Notes Anywhere is well-suited to this workflow:
read through the document once, add notes at clauses that need follow-up
or cross-referencing, and return to the annotated version for each
subsequent review without re-reading from scratch.

For long regulatory documents with sections that reference other sections,
the panel search feature lets you find a note mentioning a specific clause
number without navigating back to its position in the document.

PDF annotation for collaborative review

When reviewing a draft document or spec sent as a PDF, you can use
Sticky Notes Anywhere to add your feedback directly on the hosted PDF page
(if the PDF is served via a URL). This works well when the PDF is on a
shared internal server and you want to note your comments without emailing
a marked-up version back.

The limitation is that your notes are only visible to you, in your browser.
For comments that need to be seen by the document author, you'll need to
either use Adobe Acrobat's comment system (which embeds in the PDF) or
a dedicated review tool. But for your own reading notes and questions
to follow up on during a review meeting, the sticky notes approach is fast.

For academic reading workflows

Researchers who read papers in PDF format often accumulate dozens of papers
per project. A common workflow:

1. Download papers to a watched folder that syncs to a web server
2. Open papers via their permanent URLs (DOI links or institutional repository URLs)
3. Annotate with Sticky Notes Anywhere as you read
4. The notes are indexed by URL in the extension panel, searchable by text

The URL-based indexing means searching your notes for a term like
propagation delay shows all your notes across all papers where you
wrote about that concept — a lightweight personal knowledge graph.