2sBrain:AI PDF Document Reader

Turn complex PDFs into actionable knowledge in seconds. AI-powered summaries, smart flashcards, and your personal second brain. Download 2sBrain today!

2sBrain — Your second brain, powered by AI.

You read a lot but remember little? Documents, books, and notes scattered everywhere, slowly forgotten? 2sBrain turns them all into a personal knowledge base: AI reads for you, summarizes, connects knowledge across documents, and answers any question — based on exactly what you've added.

ADD DOCUMENTS FROM ANY SOURCE • Scan books and paper documents with your camera — capture multiple pages in a row, AI analyzes instantly • Upload PDFs and many other file formats • Write notes in a rich text editor, insert images, one tap for AI analysis

CHAT WITH YOUR OWN KNOWLEDGE BASE • Talk to the AI Assistant about your documents: summarize, explain, compare • Every answer comes with document sources and related concepts • Save valuable insights so your knowledge keeps growing and evolving over time

KNOWLEDGE WIKI — CONNECTED KNOWLEDGE • AI extracts core concepts from each document • Concepts are cross-linked between documents into your personal knowledge graph • The more you add, the smarter your second brain becomes

ANNOTATE & SIGN PDFS DIRECTLY • Highlight key passages and draw freely with a full pen kit: pencil, ink pen, marker, eraser, ruler, and custom colors • Add your signature to documents — sign contracts and forms right on your phone, no printing needed • Insert text notes anywhere on the page • Undo, erase, and edit freely; every change is saved right into the document • Feels like writing on real paper — but never gets lost

LEARN LANGUAGES FROM WHAT YOU READ • Tap any word while reading for an instant definition, without leaving the page • Smart dictionary auto-detects the language: English, Chinese, Japanese, Korean, German, Vietnamese • Save words to vocabulary notebooks by topic • Review with flashcards — flip and swipe through your words

SYNC ACROSS ALL YOUR DEVICES • Use it instantly without an account; your data stays safe on your device • Sign in to sync documents, notebooks, and chat history across devices

2sBrain is for students preparing for exams, engineers reading technical docs, language learners, and anyone who wants what they read to actually stick.

Download 2sBrain for free — and start building your second brain today.