Stop reading. Start thinking.
Vertical scroll is a cage. Work on an infinite canvas instead: notes, diagrams, web searches. Visual, freeform. The path you took stays on screen.
For students, researchers, and curious readers who refuse to outsource thinking to AI.
Made possible by open source
Libritus stands on the shoulders of the open source projects above. To every maintainer who has contributed to them: thank you.
Product north
Think with the text
AI makes it easy to skip the hard part. Libritus keeps your brain in the work.
Read to research
Open a PDF to investigate it. Annotate. Capture a search. Sketch a diagram. Pin a reference. Thinking around the text is the point.
Canvas owns research
Notes, diagrams, links, and captures live on the canvas with the PDF. Open it again later and you can still follow what you were figuring out.
AI is subordinate
No auto-summarize. No auto-highlight. No auto-keywords. Ask when you want an answer. The app will not push you to let AI read for you.
Beyond the vertical reader
Whiteboard space for a PDF
Most PDF apps are a tall strip of pages. Libritus puts the document on an infinite whiteboard. Pan. Zoom. Keep highlights, notes, freehand, and captures on the same scene as the text.
- Pan and zoom like a whiteboard, not a document scroll
- Virtualized pages so large PDFs stay usable
- The canvas holds the investigation. Not a research sidebar.
Features
Your work stays on the canvas
Investigate a PDF without dumping the trail into another app or a research sidebar.
Infinite PDF canvas
Pan and zoom virtualized pages on a whiteboard, rendered by PDFium. The document is the axis. The space around it is yours.
Highlights from selection
Select text and lock a highlight onto the canvas. Color it, copy the text, or grow a note or search from it.
WYSIWYG notes
Drop a rich note anywhere, or grow one from a highlight. It sits next to the passage that sparked it.
Web search capture
Search from a highlight, place a browser, or paste or drop a link onto the canvas. Browse in-app, then pin a screenshot beside the text. Drop images from your browser too.
Freehand and diagrams
Arrows, shapes, and sketches with Excalidraw tools, drawn on top of the PDF.
Outline, thumbs, annotations
Jump via outline, page thumbs, or a list of your highlights, notes, captures, and canvas images. The sidebar finds your place. Research stays on the canvas.
Sessions that persist
Camera and annotations autosave per PDF. Come back and continue where you stopped. Everything stays on your machine — fully offline, nothing leaves your PC.