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Zettle Notes Whitepaper

Executive Summary

Zettle Notes is a cross-platform, feature-rich note-taking app. It uniquely combines markdown editing, real-time synchronization, advanced Excalidraw-based diagramming, AI-powered voice transcription, and robust security—delivering a seamless experience on desktop (Windows, macOS, Linux) and mobile (iOS, Android).

Problem Statement & Market Opportunity

  • Fragmented Workflows: Users juggle multiple apps for text notes, diagrams, and voice memos—leading to context switching and data silos.
  • Privacy Concerns: Cloud-only solutions expose sensitive data.
  • Platform Inconsistency: Many tools lack parity between desktop and mobile UX.
  • Scalability & Offline Needs: Professionals require fast access and offline support for large note repositories.

Opportunity: A single, secure, offline-first app that natively integrates text, diagrams, and voice with real-time sync fills a critical gap.

Solution Overview

  • Unified Workspace: Inline markdown editor, embedded diagrams, multimedia, and voice capture in one app.
  • Cross-Platform Parity: Specific codebase for each platform, consistent UX across desktop and mobile.
  • Offline-First Architecture: Local first storage with automatic sync (paid).
  • Privacy & Security: AES-256 encrypted local storage and more advanced security to come.
  • AI Augmentation: On-device Whisper transcription and future AI-driven summarization.

AI/ML: Whisper Integration

  • Local: ONNX or PyTorch Mobile via FFI for privacy.
  • Server-side: Optional hosted transcription with SSL/TLS encryption.

Key Features

Note Editing

  • Markdown editor with edit/preview toggle.
  • Unsaved-changes detection.
  • Versioned note models for migrations.

Diagramming

  • Inline Excalidraw-based canvas widget.
  • JSON serialization of shapes and connectors.
  • Offline persistence and sync.

Real-Time Sync

  • Snapshot listeners.
  • Manual and automatic sync controls.
  • Conflict resolution strategies.

Voice Transcription

  • Whisper Tiny/Base models for on-device transcription.
  • Optional server-side fallback for low-end hardware.
  • Voice-command integrations.

Settings

Modular settings UI: General, Appearance, Security, AI, Accessibility, Sync, Diagramming, About.

Security & Privacy

  • Local Encryption: AES-256 via Pointy Castle for note content.
  • Secure Storage: Platform-specific secure storage for tokens.
  • Authentication: Password lock and all the security you need.
  • Security Rules: Per-user document isolation.
  • Network Security: SSL/TLS for all external communication.

Conclusion

Zettle Notes delivers a powerful, secure, and versatile note-taking platform that unifies text, diagrams, and voice in a single app. Its modular architecture, offline-first design, and AI-enhanced features position it to redefine productivity workflows across devices.