S4

Digital Note-Taking Apps

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This application integrates markdown note-taking with intelligent spaced repetition flashcards to improve active learning, retention, and knowledge visualization for students, professionals, and academics. Its main features include embedding flashcards directly within markdown notes, visualizing interconnected notes through interactive knowledge graphs, drawing occlusion rectangles over diagrams and images, snipping PDFs with source citations, and using local semantic search, all operating offline within a secure, local environment. It addresses common challenges such as seamless knowledge organization, efficient review scheduling, and maintaining data privacy, making it ideal for users seeking a flexible, open-source system for studying, professional development, and academic research.

S4 can be found in Digital Note-Taking Apps categories.

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Details

S4 Main Features

• Free to use
  S4 is free and does not require an account to operate locally.
• Works offline
  You can write, review, and access your notes without internet.
• Knowledge graph
  See how your notes are connected in an interactive visual graph.
• Semantic search
  Find notes by meaning, even if the exact words are not written.
• Available for Mac
  Download S4 for macOS now; Windows and Linux are coming soon.
• Local review data
  Review information is stored in a local SQLite database, easy to back up or export.
• Spaced repetition
  S4 schedules reviews so you remember better, showing difficult cards sooner.
• Remember everything
  You can save and keep all your notes and flashcards in one place.
• Sync across devices
  Your progress and cards sync automatically between your computer and phone.
• Review on your phone
  Create an account to use S4 on your phone or tablet as a web app.
• Runs on your machine
  Everything works on your computer without needing an internet connection or account.
• Snip regions from PDFs
  Cut out parts of PDFs with citation links to source pages.
• Write and review easily
  Write your notes and flashcards once and review them smartly.
• Compatible with Obsidian
  Use S4 with your existing markdown files and vaults without importing or lock-in.
• Extract text from images
  Use Vision OCR to turn images into text with LaTeX in markdown.
• Draw occlusion rectangles
  Draw boxes over diagrams, images, or maps to hide and reveal parts of it.
• Works with markdown editors
  S4 works alongside existing tools like markdown editors, not replace them.
• Create flashcards in markdown
  Make flashcards directly in markdown, including tables, LaTeX, and code blocks.
• Notes and flashcards together
  Your notes and flashcards stay in the same system, making learning easier.

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S4 Alternatives

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Technologies Used

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