massCode is a local-first desktop application designed for developers who want to centralize their everyday coding tasks—snippets, documentation, calculations, and utilities—without leaving their machine. It eliminates the friction of switching between editors, note apps, calculators, and web tools by integrating all these functions into one cohesive workspace. Built with Electron, Vue, and Vite, it runs natively on macOS, Windows, and Linux, and stores all data as plain Markdown files with frontmatter for portability and Git compatibility.
The app’s ecosystem includes integrations with VS Code and Raycast for seamless snippet access, supports 160+ syntax languages via CodeMirror and .tmLanguage files, and features real-time previews, Mermaid diagrams, JSON visualizers, and live currency conversions. Its local-first architecture ensures no vendor lock-in, with full support for cloud sync via iCloud, Dropbox, Google Drive, and Syncthing.
What You Get
- Code Snippets with Prettier & HTML/CSS Preview - Edit code across 160+ languages with real-time HTML/CSS rendering and automatic formatting via Prettier, with export options for polished images.
- JSON Visualizer - Interactively explore and navigate nested JSON structures as expandable graphs directly in the editor.
- Markdown Notes with Mermaid & Mind Maps - Write technical docs and knowledge base entries with live preview, embedded Mermaid diagrams, and automatic mind maps generated from heading hierarchies.
- Math Notebook with Live Calculations - Perform natural-language math including currency conversions (166+ fiat, 21 crypto), date math, unit conversions, and finance formulas like ROI and compound interest with instant results.
- Developer Tools Suite - Built-in utilities for Base64 encoding, URL parsing, UUID generation, password generation, JSON-to-YAML/TOML/XML conversion, and color hex/RGB conversion.
- Markdown Vault with Git & Cloud Sync - All snippets and notes are stored as plain .md files with frontmatter, enabling full Git versioning and real-time sync with iCloud, Dropbox, Google Drive, and Syncthing.
Common Use Cases
- Managing cross-project code snippets - A full-stack developer organizes reusable React components, API endpoints, and shell scripts in massCode, tagging them by language and project, then exports them as images for documentation.
- Maintaining technical documentation - A DevOps engineer writes and updates infrastructure guides in Markdown with embedded Mermaid diagrams, syncing them via Git to a private repo while using live preview to check formatting.
- Running quick financial or unit calculations - A product manager calculates ROI for a SaaS feature using natural-language inputs like “$500 invested, $1,500 returned” or converts 100MB to bits without opening a browser.
- Syncing notes across devices without cloud lock-in - A freelance developer uses massCode with Syncthing to keep their snippet library and project notes in sync between their Mac and Linux workstation, with full file access and no proprietary format.
Under The Hood
Architecture
- Electron-based architecture with clear separation between main (Node.js) and renderer (Vue) processes, enabling secure and efficient inter-process communication
- Centralized state management via modular store modules (app, currencyRates, preferences, mathNotebook) that encapsulate domain logic and side effects with single-responsibility principles
- Elysia.js exposes secure REST APIs for system-level operations, while Vue 3 components leverage composable utilities and typed variant systems for consistent UI primitives
- Dependency injection is handled through module exports and TypeScript interfaces, ensuring type safety without formal DI containers
Tech Stack
- Electron for desktop packaging with cross-platform support, paired with Vue 3 and Vite for a responsive, type-safe frontend
- CodeMirror 5 and 6 with Lezer provide advanced syntax highlighting and Markdown editing, while SQLite via better-sqlite3 handles local snippet storage with migration support
- Elysia.js powers lightweight, type-safe API routes with built-in Swagger documentation, and Electron Builder enables polished native packaging
- Vitest ensures robust test coverage, while Tailwind CSS and shadcn-vue form a cohesive, component-driven UI system
Code Quality
- Extensive test coverage across core domains with precise dependency mocking and state isolation for reliable validation
- Strong TypeScript enforcement through well-defined interfaces and validation layers, ensuring data integrity from storage to UI
- Consistent naming conventions and modular organization promote readability and maintainability, with clear separation between storage, composables, and components
- Robust error handling with domain-specific exceptions and graceful degradation strategies, though custom error classes are inconsistently applied
What Makes It Unique
- Native integration of TextMate grammar definitions enables rich syntax highlighting for niche languages without external dependencies
- Dynamic code generation powered by localized, context-aware Faker.js templates that adapt to UI language settings
- Real-time currency rate aggregation with intelligent fallbacks and source transparency, enhancing reliability in offline scenarios
- Extensible tag system that synchronizes note metadata across the app in real time, eliminating manual state management
- Built-in devtools generator with drag-and-drop configuration for JSON modeling, tightly coupled with the editor’s grammar system for consistency