massCodeYour developer workspace
Manage code snippets, write markdown notes, solve calculations, and use built-in developer tools. Free, open source, and works offline.
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Code Snippets
Build a reusable code library across projects and languages. Organize snippets with folders, tags, and fragments, then edit them with CodeMirror , format them with Prettier , preview HTML & CSS in real time, inspect JSON visually, and export polished screenshots when you need to share code.
Notes
Keep technical notes, docs, and drafts next to your snippets. Write in Markdown with live preview, folders, tags, Mermaid diagrams, mindmaps generated from headings, and fullscreen presentation mode for sharing your work.
Math Notebook
Do the quick calculations that usually break your flow. Natural-language math handles inputs like
time in Tokyo, density of honey, and $500 invested $1,500 returned for currencies, time zones, unit conversion, finance, and date math. Developer Tools
Handle the small developer tasks that usually send you to a browser tab. Convert, encode, hash, and generate data right inside massCode with tools for JSON, Base64, URLs, colors, passwords, UUIDs, and more.
Integrations
Bring your snippet library into the tools you already use. VS Code Extension for searching and inserting snippets, and Raycast Extension for quick access from anywhere.
Open & Local
Keep your data on your machine and in your control. Notes and snippets are stored as plain Markdown files, so syncing with iCloud, Dropbox, or Git stays simple and portable.
Localization
Use massCode in the language you are most comfortable with. The app is available in 15 languages, including English, Deutsch, Español, Français, Русский, 日本語, and 中文.