School
Grade books, quizzes, lab sheets. Student data that never leaves the device.
Open the example →Write a document
Get an app
Reactive turns a Markdown document into an interactive application — persistent data, Python computation and charts — running entirely in the browser. No account, no data ever leaves your device.
The document is the app
Document on the left, live app on the right: every change shows up instantly. What you see is a complete grade book — form, editable table and reactive average — in 24 lines of text.
How it works
1
Write
Standard Markdown plus simple directives: ::input, :::list, :sum. Or describe the app to the local AI assistant and let it write the document.
2
The browser compiles
No server, no build step: the document becomes an interactive app as you type, and the data stays saved on your device.
3
Use and share
An app is a file: share it with a link. With encrypted sync, whoever receives it works on the same data in real time.
Made for your world
Four ready-made examples: open one and it's yours — working, editable and private. No sign-up.
Small business
Inventories, bookings, quotes: full CRUD and reactive totals, no ERP required.
Open the example →Personal
Budgets, lists, habit trackers: your data stays in your browser, by construction.
Open the example →Teams
Tasks and data shared in real time, end-to-end encrypted: the server can't read them.
Open the example →Why Reactive
No server, no account
Everything runs in the browser. Nothing to install or configure, no sign-up, no subscription: open it and use it.
Privacy by construction
Data is never transmitted: it stays in the browser, isolated per app. Suitable for personal, school and business data alike.
Real Python in the browser
Actual Python (WebAssembly), with numpy, pandas and matplotlib. Code reads the app’s data and produces charts that update on their own.
Apps are files
An app is a Markdown document: create it, save it, share it, put it under version control. No proprietary format.
E2E-encrypted collaboration
A secret in the file enables multi-user sync: conflict-free merges (CRDT) and a relay that only ever forwards ciphertext.
Local AI assistant
An optional chat, running locally via Ollama, helps you author the document with targeted, reviewable edits. No cloud, no API keys.
Your apps, one library
Every app you open or create lives in your library: launch it, rename it, duplicate it, export it as an .md file — and share it with a link.
What you can build
Section titled “What you can build”Data-entry forms with full CRUD, lists, cards and tables with filtered, sorted and grouped views, reactive statistics, Mermaid diagrams, math formulas and Python analysis with charts — all by writing text.
Start with the step-by-step guide, browse the complete tag reference or explore the example apps.
Ready to try?
It opens and runs right in your browser: no install, no sign-up, and the data stays yours.
Open app.reactivenet.ai