A typing test that learns where you're slow.

Every keystroke you type is timestamped against the character you were aiming for. From that stream we extract three per-symbol stats: how fast you hit each bigram (letter pair), each trigram (three-letter sequence), and each individual word. Mean and variance update online with Welford's algorithm so the model converges quickly and doesn't blow up memory.

On every fresh practice run, the algorithm picks words that stress your slowest pairs — not random ones, not the most common ones, but the ones holding your overall speed back. Over time the same bigrams you missed early start firing as fast as your fastest. You can see the per-bigram heatmap and the current weakness ranking on your insights page once you're signed in.

The race surface puts you against deterministic bots out of the box — three difficulty tiers across four passage modes — but real multiplayer matchmaking is one click away. Press Find race and we look for real players for up to five seconds; if none show, bots fill the empty seats so your run isn't blocked on someone else being online.

Create lobby spins up a private challenge room and gives you a short friendly URL (e.g. quick-otter-42) to share with a friend. Anyone who clicks the link drops into your lobby; you press start when you're ready.

Everything is free. The site is open source, the practice surface and races run without an account, and there are no ads on any page. Signing in with Clerk unlocks per-user history, the personal-best tracker, and adaptive-drill persistence — the model needs a home between sessions for those to mean anything.

QWERTY, Dvorak, and Colemak are all supported — pick yours from the customise page so the adaptive engine categorises your bigrams under your real same-finger / hand-alternation map. The whole UI ships in JetBrains Mono with tabular numerics on every stat, mobile-first responsive layouts down to 375 px, and `prefers-reduced-motion` honoured everywhere.

Open the home page and start typing — that's it. The test ends on the last word. From there you can pick a different mode, head into drills, or jump into a race. Sign in to persist your history; the rest works without one.