Highlight, annotate, and export any PDF
Upload any PDF and start highlighting with semantic colors. Each highlight carries meaning you define. Export as structured JSON for AI tools, or connect directly via MCP. Your annotations become searchable, linkable, and AI-ready.
How it works
Three steps to get started
Upload any PDF up to 100MB
Drag in any research paper, textbook, or article. Text is extracted instantly via TUS resumable upload. Every word becomes searchable from the moment it uploads.
Highlight with meaning
Select text and tag it with a color that carries your reasoning. Yellow for key concepts, blue for questions, green for evidence. Add notes to any highlight for deeper context.
Search across everything
Find any highlight across all your documents in seconds. Filter by color, document, or keyword. Full-text search covers both your highlights and the original document text.
Who it's for
Built for how you actually read
Annotate textbooks for exam prep
Upload course PDFs and color-code by concept type. Before exams, search 'all key concepts in Chapter 5' across multiple textbooks. Never lose a highlighted definition again.
Annotate papers for literature reviews
Highlight methodology in rose, findings in sage, theoretical frameworks in amber. When writing your review, search by color to pull all methodologies from 40 papers in one query.
Annotate non-fiction with purpose
Stop treating all highlights as equal. Mark frameworks in yellow, questions in blue, disagreements in rose. Three months later, you can search 'all frameworks from Atomic Habits' instantly.
Frequently asked questions
What is the best app for PDF annotation?+
Highlyt is a PDF annotation tool designed for students, researchers, and book readers who want their highlights to do more than just mark text. Each color carries a meaning you define, highlights link into a knowledge graph, and everything exports to AI tools via MCP or JSON.
What's the maximum file size?+
Pro accounts can upload PDFs up to 100MB each with unlimited documents. Free trial allows 3 documents up to 25MB each. Upload uses TUS resumable protocol so large files won't fail on slow connections.
Does Highlyt work with scanned PDFs?+
Highlyt works best with text-based PDFs where the text layer is present. Scanned documents (images of text) have limited support. We recommend running OCR software first for scanned documents.
Can I annotate PDFs on iPad?+
Yes. Highlyt is a web app that works in Safari on iPad. You get the same highlighting, color-coding, and search features. Your annotations sync across all devices automatically.
Your next book deserves better than a yellow highlighter
Every book and paper you read builds your knowledge. Highlyt makes sure none of it gets lost. Start your free trial and turn scattered highlights into a connected, searchable, AI-ready knowledge base.