How do I highlight a PDF in Chrome?
Short answer
Chrome's built in PDF viewer is closed to extensions, so web highlighters cannot mark PDFs there. Open the PDF in a viewer that supports annotations: a tool's own PDF viewer, Zotero, or Obsidian with the PDF++ plugin. Lumen's own PDF viewer is in progress.
Step by step
- Download the PDF.
- Open it in Zotero or in Obsidian with PDF++ to highlight.
- Or wait for Lumen's PDF viewer, which opens PDF links in its own page.
Good to know
Tools that highlight PDFs in the browser (Hypothesis, Glasp, Readwise) all open the file in their own viewer built on pdf.js.
Related questions
Answer
Can Lumen highlight PDFs today?
Not yet. It is on the roadmap as the next format.
Updated 2026-11-01.