massCode

A free, open-source developer workspace.

Snippets, notes, HTTP requests, calculations, drawings, and dev tools in one local-first app.
Your data stays on your machine as plain Markdown files.

Download  |  Documentation  |  Changelog

Extensions: VS Code | Raycast

_{Available for macOS, Windows, and Linux}

Support

massCode is free and open source. But building and maintaining a quality tool takes time. Your support helps keep development going and new features coming.

SPONSORS

About

Originally a snippet manager, massCode now brings together snippets, notes, HTTP requests, calculations, drawings, and developer tools in one desktop app, so everyday work stays in one place.

Features

Code Snippets

Use massCode as a focused snippet workspace with multi-level folders, tags, and fragments for organizing reusable code across projects and languages.

• 160+ syntax grammars out of the box (600+ supported via .tmLanguage)
• Integrated Prettier for code formatting
• Real-time HTML & CSS preview for quick prototyping
• JSON Visualizer for exploring nested structures as interactive graphs
• Export snippets as polished images with customizable themes

Notes

Write longer markdown documents right next to your snippets: project docs, drafts, research notes, and personal knowledge bases.

• Task notes with status, priority, due dates, and Today / Upcoming / Completed views
• Completed task cleanup and auto-clean scheduling
• Dashboard with activity overview, recent notes, top linked notes, and a notes graph preview
• Editor, Live Preview, and Preview modes
• Editable markdown tables with row and column controls
• Fullscreen notes graph for exploring internal links between notes
• Integrated Mermaid diagrams
• Mind maps generated from markdown heading structure
• Fullscreen presentation mode for demos and meetings
• Callout blocks and image embedding

HTTP Client

Keep API requests close to your code snippets and project notes with a lightweight HTTP client built into massCode.

• Organize requests with folders and custom folder icons
• Use environments and {{variables}} for local, staging, and production APIs
• Edit params, headers, body, auth, and markdown descriptions
• Preview requests as raw HTTP or cURL before sending
• Inspect response status, time, size, body, and headers
• Send the current request with Cmd+Enter on macOS or Ctrl+Enter on Windows and Linux

Math Notebook

A calculator-style notebook for natural-language calculations, conversions, and date math without leaving your workflow.

• Arithmetic, percentages, unit conversions, and date/time math
• 166+ fiat currencies, 21 cryptocurrencies with live exchange rates
• Variables, functions, and aggregates for quick iterative calculations
• Finance calculations (compound interest, ROI, loan repayment)

Drawings

Sketch diagrams, wireframes, and whiteboard ideas on an Excalidraw-powered canvas next to your snippets and notes.

• Searchable list of drawings with keyboard navigation
• Pan and zoom remembered per drawing, with fit-to-content to recenter
• Export drawings as images
• Embed drawings directly in your markdown notes

Developer Tools

Built-in utilities for the small tasks that usually send you to a browser tab:

• Compare: JSON Diff
• Text: Case Converter, Slug Generator, URL Parser, Line Break Normalizer
• Crypto: Hash/HMAC Generator, Password Generator, UUID
• Encoders: URL, Base64, JSON to TOML/XML/YAML, Color Converter
• Generators: JSON Generator, Lorem Ipsum

Command Palette

Jump to spaces, snippets, notes, HTTP requests, and common actions from anywhere with a keyboard-first command palette.

• Open with Cmd+P on macOS or Ctrl+P on Windows and Linux
• Search across snippets, notes, HTTP requests, spaces, and commands
• Run create actions for snippets, notes, HTTP requests, and folders
• Scope search to a space with @ or open command mode with >

Imports

Bring existing work into your vault with preview-first imports for snippets, notes, and API collections.

• Import snippets from VS Code, Raycast, SnippetsLab, and public GitHub Gists
• Import markdown notes from Obsidian folders
• Import HTTP collections from OpenAPI, Postman, and Bruno
• Review detected items, folders, tags, environments, and warnings before writing anything

Browser Clipper

Save web content from Chrome, Firefox, or Safari into the local massCode app.

• Install the Chrome version from the Chrome Web Store
• Save selected code as snippets
• Save selected text or readable page content as notes
• Save pages or links as HTTP GET requests
• Connect through the local Integration API with an API token

Markdown Vault

Your snippets, notes, and HTTP requests live as plain .md files on disk with frontmatter metadata, so the data stays readable and portable.

• Git-friendly - track changes and sync via any Git remote
• Cloud sync - works with iCloud, Dropbox, Google Drive, Syncthing
• Live sync - massCode watches the vault and picks up external changes in real time
• No vendor lock-in - your data is always yours

Custom Themes

Customize the app UI and editor syntax highlighting with JSON theme files. Supports light and dark themes with live reload. See the theme docs.

Build Locally

pnpm install

pnpm build

pnpm build:mac    # macOS
pnpm build:win    # Windows
pnpm build:linux  # Linux

pnpm dev

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• News and updates on X
• Discussions

License

AGPL-3.0

Copyright (c) 2019-present, Anton Reshetov.