A spreadsheet editor that opens and saves real .xlsx files — formulas, formatting, charts — compiled to WebAssembly from the open-source GridCraft project. Everything runs on your device; nothing you open is ever uploaded.
Before you click Launch: this loads a ~16MB WebAssembly app (same engine as the native desktop build), so give it a moment on a slow connection. It's also alpha upstream's own words — the core workflow works end to end and covers most of the Excel ribbon, but depth, fidelity and file compatibility are still rough. Works best in a browser with WebGPU or WebGL2.
How it works
GridCraft's whole engine and UI compile to WebAssembly from the same Rust codebase as the native app, so it's loaded once (on Launch, not on page load) and then runs as a self-contained spreadsheet inside the frame above — editing and saving a workbook never leaves your browser. The GPU path uses WebGPU where available and falls back to WebGL2 automatically.
FAQ
Does my spreadsheet get uploaded anywhere?
No. GridCraft runs entirely client-side via WebAssembly — editing and saving all happen on your device. There is no server-side document storage.
Why is the download so big?
It's a full spreadsheet engine, not a small script — about 16MB of WebAssembly, the same engine that powers the native desktop app. It only loads once you click Launch, and your browser caches it after that.
Is this finished software?
No — GridCraft is alpha, upstream's own words. The core workflow works end to end and covers most of the Excel ribbon, but depth, fidelity and file compatibility are still rough.
Free, unlimited, no account. If this saved you a paid tool, a small thanks is appreciated.