The whole app is 96 KB.

The timetable engine is written in Rust and compiled to WebAssembly, which your browser turns into native machine code — no interpreter, no garbage-collected runtime between the algorithm and the CPU.

It generates over half a million valid timetables per second in the browser, and over 750,000 per second natively. A real five-subject selection — 19,638 valid timetables — is done in about 36 milliseconds, just over two frames of a 60 Hz screen.

Each subject has only a handful of distinct ways it can be scheduled. The engine computes those once, and stores every result as one 16-bit number per subject — an index into that small list — instead of copying teachers, venues, and slots into every timetable.

A complete five-subject timetable costs 10 bytes. All 19,638 of them fit in under 200 KB of memory. Ranking them all by idle time takes about 4 milliseconds.

• No server. Not a fast server — none at all. Lattice is a few static files.
• No database, no account, no sign-in. Your subjects live in your own browser.
• No cookies, no analytics, no trackers, no ads.
• No web fonts, no icon library, no UI framework bundle. The eight icons are drawn inline; dialogs, dropdowns, and popovers are the browser's own.
• One runtime dependency. Preact, at about 6 KB.

• Small code loads fast on a weak phone and a crowded hostel Wi-Fi.
• Nothing to wait on after it loads — every generate, re-rank, and preference change runs on your device.
• Install it like an app, and it opens with no internet at all.
• Nothing to break, leak, or go down. There's no backend to have an outage.