Stack is Tauri 2, Rust, SolidJS. The render and spreadsheet engines are both custom, compiled to WASM with modified PDFium for parsing. One codebase builds native Mac and Windows.
Performance is most of the work. A 500-sheet set opens in about a second. Million+ vector drawings hold 120 FPS on mid hardware. It feels somewhat faster that any other construction viewer I’ve tested. Compare the live demo (on the homepage, or download free trial) vs an industry standard pdf tool at showcase.apryse.com/cad-viewer. The solver runs 11-15M dependency steps/sec on an adversarial test.
Perhaps most important engineering achievement is that RAM & Performance scale strictly with active attention rather than project/file scope for both engines. So the same 1000 cell viewport renders at the same speed whether it is 1000 cells total or 1000 out of 10M in a sheet. Similarly page 1 of 500 is as performant as page 1 of 1. This is crucial in the space because with projects often having 10K-100k+ drawing versions, anything that scales with project size crashes. This is why (I think) incumbents can’t have reactive, connected sheets across large sets/projects. Traditional spreadsheet architecture (DAG in RAM) would crash. More on the engineering here: https://purple-hammer.com/blog/ai-friendly-architecture.html
Closed source, free trial available. AMA