2sBrain vs Index

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.

Save anything. Think with everything. Index is a personal knowledge workspace for the context you do not want to lose. Share a link, note, or document from your iPhone, and it becomes part of a calm, organized brain you can return to later. ASK YOUR BRAIN Discuss complex ideas across everything you have saved. Index grounds answers in your own context and links citations back to each source. CAPTURE WITHOUT BREAKING FOCUS Use the iOS share sheet to save useful links, selected text, files, and quick notes in seconds. TURN LINKS INTO CONTEXT Index extracts readable page content, creates a concise summary, and keeps your own note beside it. STAY IN CONTROL Your account syncs across devices. Delete individual items and conversations whenever you want, or permanently delete your account and its captures, files, chats, and feedback from inside the app. Built for founders, researchers, and knowledge workers who want less friction between finding something useful and thinking with it. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://index-legal.vercel.app/privacy