jevchess
One-page web app where Jev plays chess against OpenRouter LLMs, Stockfish or you, showing the moves it weighed and their probabilities.
Overview
Jev Chess lets you watch Jev play chess against any LLM on OpenRouter or the Stockfish engine, or play it yourself. Code owns the game: chess.js lists every legal move, code describes what each move does in words, and Jev picks among them with calibrated probabilities; it does not search ahead. Every move is shown live with arrows for the moves Jev considered and their probabilities, and every finished game is saved for replay, PGN copy or sharing.
In Jev versus machines mode, you can run games against several Stockfish strengths (Elo 1320 to full strength) and many LLMs at once on a split screen, then see Jev's wins, draws and losses against each, time per move, how often an LLM failed to name a legal move, and the cost. In you versus Jev mode you can drag pieces, type moves or speak them, and Jev resolves loose phrasing like put my knight on f3 by picking the legal move the words name, answering in about a third of a second. The README's tour shows Stockfish 1320 beating Jev and Jev mating Mercury 2.5 in 11 moves. The hosted site lends capped keys; your own keys lift the cap. MIT licensed.
What the decision model decides
| Type | Question | Answers |
|---|---|---|
| Choice | Which legal move (described in words) should Jev play? | — |
| Choice | Which legal move do the user's spoken words name? | — |
How it works
- chess.js lists legal moves
- Code describes each move's effect in words
- Jev picks a move with probabilities
- Play, display arrows and probabilities, save the game
Strengths
- Live hosted demo with lent keys
- Side-by-side comparison with LLMs and Stockfish
- Voice move resolution via Choice over legal moves
Caveats
- No lookahead; loses to low-level Stockfish in the tour
- Voice in Chrome sends audio to Google
Getting started
Play at https://jevchess.xera.ac with no key, or add your own OpenRouter or TypeSafe key.At a glance
- Type
- App
- Status
- beta
- Language
- JavaScript
- Runtime
- Web app
- Has code
- yes
- License
- MIT
Use cases and integrations
How curated lists describe it
Jev, TypeSafe's System One model, plays chess against any OpenRouter LLM, Stockfish and you. One-page web app with live moves, Jev's move probabilities, saved games and win rates.
logicrw/awesome-jev-projectsJev, TypeSafe's System One model, plays chess against any OpenRouter LLM, Stockfish and you. One-page web app with live moves, Jev's move probabilities, saved games and win rates.
hellogumbo/awesome-jev
Frequently asked questions
Does Jev search ahead?
No, it picks among legal moves described in words without lookahead.
How strong is it?
In the README's tour, Stockfish at Elo 1320 beat Jev, while Jev mated Mercury 2.5 in 11 moves.
Can I play by voice?
Yes, and Jev resolves loose phrasing to a legal move.
Related projects
Two Jev benchmarks with a playground: chess (out of lane, about 950 Elo with code-supplied facts) and NPC addressee detection (F1 0.96).
BenchmarkresearchPythonFifteen live arcade games where Jev and LLMs play each other, led by WikiRace in which Jev picks only real links.
ProjectbetaTypeScriptPac-Man where Jev or other System One models choose each move at junctions, with live odds, fallbacks and a leaderboard.
ProjectbetaTypeScriptBrowser chess lab where Jev, LLMs and people play, each Jev turn being one Choice over the legal moves, with Stockfish analysis.
ProjectbetaPythonNiceGUI desktop chess app for evaluating Jev's move choices against Stockfish, random players or itself, with PGN export.
ProjectprototypePythonBrowser 2D driving sim where Jev answers lane, speed, hazard and pedestrian-yield questions every 200 ms, with an LLM comparison mode.
ProjectprototypeJavaScript