Chess Teacher - Stockfish, Maia & Hands-free Voice

Black - top

BW0.00

White - bottom

No moves yet.

Hints & display

Show white hints Show black hints Commentary

Loading chess rules...

Saved game on this device

The board position, complete move history, engine choice, strength, mode, Allow Blunder, hint switches and board orientation save automatically in this browser. Reopening this same site restores them. If it is the computer's turn, it resumes after a fresh analysis.

New game replaces the saved position but keeps your settings. This saves one game per browser profile and site folder, not a cloud backup. Private browsing or clearing site data may erase it. Localhost and GitHub Pages have separate saves.

Hands-free voice (optional) Microphone off

Mouse play is always available. To use voice, start once, say coordinates, then say "move" after the green preview appears.

Voice settings, typed correction & setup

Speech Language

Heard / edit

Whisper pause

Click-to-move remains the default and always works. Hands-free is optional: start it once, say C two to C four, pause for the single green destination, then say move as a separate command. Say D two to D four to replace the preview; no piece moves until confirmed. Say cancel to clear the preview, or stop listening to turn the microphone off. Clicking the board clears the voice preview and takes priority.

Phonetic coordinates (Charlie two to Charlie four), castle kingside, and E seven to E eight promote to queen are supported. A promotion without a piece first asks you to say queen, rook, bishop or knight; then confirm with move. In Play computer, speech controls only your bottom-side pieces. It waits through the computer turn and is ready again automatically.

Whisper: copy your oral-exam wasm/stream.js and its matching companion files into this site's wasm/ folder, plus models/ggml-base.en-q5_1.bin. Alternatively run py -3 install-voice.py from this app folder. The helper voice-coi-serviceworker.js must be beside index.html. Prepare voice may reload this page once to enable local WASM threads; your game is saved first. No speech model loads until you request it.

Browser on-device: requires actual processLocally support and an installed language pack. Prepare voice checks/downloads the chosen pack. Unsupported browsers show an error rather than using a cloud recogniser. Both methods require microphone permission and HTTPS (GitHub Pages) or localhost.

Whisper processes each short phrase locally after a pause. Wait until Listening is shown before your next command; audio spoken while it is processing or while the computer moves is discarded, not queued. Browser recognition processes final results only. There is no immediate-play option: coordinates always create a preview first. Ordinary moves keep hands-free enabled; New game, Undo, engine/side/settings changes, hiding the tab, closing this panel, or Escape turn it off. Microphone access never starts automatically on reload. Audio and transcripts are not saved or uploaded. Voice setup and privacy notes.

Computer move selection

Weighting Think limit

The computer plays the top colour. You play the bottom colour.

Allow Blunder and move probabilities

Unchecked: use Stockfish's final bestmove, with no intentional random choice. This is the best move found within the selected search budget, not a promise that it is objectively perfect. The weighting selector is disabled.

Checked (default): preserve the existing weighted draw among the four best candidates. Allowing a lower-ranked move does not force a blunder, and the top four may all be good moves.

Both choices retain your rank bonuses: 20%, 10%, 5%, 0%, then normalise the preliminary weights to total 100%. Percentages mean chance of selecting a move, not chance of winning.

Score-gap: using scores in pawn units from the moving side's viewpoint, calculate w = exp((score - bestScore) / 1.0). The preliminary weight is rankBonus + w / sum(w). This keeps the score order intact with positive, zero, or negative evaluations.

Your formula: use rankBonus + score / totalScore. When the signed total is zero or negative, use the sum of absolute scores as the denominator; if all scores are zero, start with equal shares. If any preliminary weight is negative, add the same amount to all so the smallest becomes 0.05, then normalise. That 5% floor is before normalising, not a minimum final chance.

Mate safeguard: take an available immediate checkmate; otherwise favour forced-mate lines over non-mating lines. Avoid an engine-reported forced loss when another candidate avoids it. Within an all-mate pool, use mate distance rather than pretending mate is a centipawn score. Fewer than four legal moves are handled automatically.

The computer waits for its search to end (depth, node budget or time limit) before choosing. A brief pause makes the reply visible. Changing engine or mode, flipping, undoing or starting a new game cancels a pending choice.

Best next moves

Waiting for engine...

Green = #1. Yellow = #2-4. Labels show rank and origin:destination. Dotted lines connect square centres. Hints apply only to the side whose turn it is.

Teacher's commentary

Waiting for analysis.

Move history

No moves yet.

About strength settings

Training estimates, not measured FIDE ratings. Stockfish presets control search budgets. Maia receives the selected number as a human-play rating input. Neither is a measured FIDE strength; the Stockfish teacher uses its preset even when Maia is playing.

Stockfish search presets and variety

These are hand-tuned search budgets, not a validated depth-to-FIDE conversion. The label 600 does not mean this engine has achieved a 600 FIDE rating. Actual strength depends on the position, engine build, thinking limit and move-selection policy. Proper rating calibration would need games against opponents with known ratings.

Training label	Depth ceiling	Node budget

Stockfish's documented UCI_Elo starts at 1320 and is anchored to an engine rating list, not FIDE. Its built-in strength reduction deliberately chooses suboptimal moves. This board instead keeps that reduction off, so your Allow Blunder checkbox has sole control over intentional random move selection.

Same position, same best move? Often, yes. Fixed single-thread search is not shuffled automatically here. Allow Blunder adds variety by sampling the best four analysed moves, without changing the preset. With it off, the board always uses the engine's final best move; even equal-score ties are not deliberately randomised. Different human opening moves also lead to different games.

The hash/search cache is cleared before each search so changing from a stronger to a weaker preset does not reuse deeper analysis. The optional time cap may stop a search before its full budget is reached. The completed depth is shown below the hints. These limits apply in Practice too, so low-level hints are not full-strength analysis.

Engine setup, source & licences

Keep the existing chess.js and Stockfish Lite files. For the extra engines, run py -3 install-models.py (Windows) or python3 install-models.py (WSL/Linux) once, from the app folder. Full Stockfish uses engine/stockfish-19-single.js and its matching WASM. Maia uses models/maia3/maia3_simplified.onnx, models/maia3/all_moves.json and the files in vendor/ort/.

All play runs locally in your browser. Engines load only when needed. There is no automatic fallback to a different opponent when an engine fails: use Retry engine or choose another model. Switching models preserves the board and move history, but restarts analysis. This choice is autosaved.

Maia model/version: the official CSSLab Maia-3 browser export, pinned to frontend commit a6e52f5. The 600-2400 choices are inputs to its rating-conditioned model, not independently measured FIDE ratings. Maia hints are listed separately; board colours and the bar remain Stockfish evaluations.

This HTML is the editable application source. Download application source · Third-party notices and corresponding sources · Setup and test notes. Preserve the relevant GPL/AGPL licences and source access when publishing, even for a free site.