Real chess engine.
On your phone.
ChessUp packs a 2300-ELO Rust engine, computer-vision board scanner, coach mode, curated puzzles, and local-Wi-Fi multiplayer with chat and emotes into one private phone app — on iPhone and Android. No accounts. No telemetry. Everything runs on-device.
Twelve tools.
One on-device app.
ChessUp is what every major chess site already does · but without the account, the tracking, or the server round-trip. Every feature runs on your phone.
Coach Mode
Every move scored · best line, threats, plans · plain-language explanations
2300-ELO Engine
Native Rust engine on-device · adjustable strength · no cloud calls
Board Scanner
Point the camera at another screen · vision pipeline writes the FEN for you
Share Extension
Share any screenshot to ChessUp · the engine returns the best move inline
Browser Extension
Analyze the active tab on every major chess site · one-tap engine eval
Local Multiplayer
Same-Wi-Fi peer-to-peer · chat and emotes · no matchmaker, no server
Messages Play
Play a full chess game inside a message thread · moves stay between you
Game History
Every game saved on-device · move-by-move replay · jump to any position
FEN Tools
Paste any FEN · open in a read-only viewer · export as PNG · analyze in one tap
Learn & Drill
Curated openings, endgames, and tactics · spaced repetition built in
Daily Puzzles
Hand-picked tactical sets · streaks and difficulty curve, fully offline
Private by Design
No account · zero telemetry · games and analyses stay on your device
See every move
the way a coach would.
Drop in a PGN, scan a board, or just play · ChessUp runs the entire position through a native Rust engine and a coach layer that names each move (Brilliant, Best, Good, Inaccuracy, Mistake, Blunder) and explains why. The engine is real, the explanations are written, the verdict is yours.
- 2300-ELO Rust engine that runs entirely on-device
- Move-by-move tags · Brilliant, Best, Good, Inaccuracy, Mistake, Blunder
- Suggested continuation lines with click-to-explore variations
- Plain-language reasoning for every critical position
The engine is yours · no positions ever leave your phone.
Point the camera.
Get a position back.
A computer-vision pipeline reads a real-world chess board and writes the FEN for you. Detect the board corners, classify every piece, and hand the position straight to the engine for analysis · all on-device, no upload.
- Board-corner detection and perspective rectification
- On-device piece classification across pieces, sides, and squares
- One-tap export to analysis, play, or PGN
- Confidence indicator with manual override per square
Vision runs locally · no photos uploaded, no third-party model calls.
Play across the table.
No servers in the middle.
Same-Wi-Fi peer-to-peer multiplayer with live chat and emotes. ChessUp builds the connection on top of our open-source ConnectionPool library · the same mesh transport from the StealthOS project, with DTLS-encrypted local pairs. No matchmaker, no game server, no account.
- Local-Wi-Fi peer-to-peer · DTLS encrypted under the hood
- In-game chat and reaction emotes during play
- Time controls, takebacks, and offered draws
- Built on the open-source ConnectionPool library from StealthOS
Transport · ConnectionPool from StealthOS · MIT
Pay what you use.
Nothing more.
Free for play, local multiplayer, and daily puzzles. A one-time $0.99 unlocks in-app analysis and the Learn track. Pro adds the on-device vision pipeline — camera scan, share extension, and browser extension.
Free
No account · forever free
Play against the engine across all four difficulty tiers, pair up over local Wi-Fi for a friend match, and keep a daily-puzzle streak. No sign-up, no internet required.
- Play vs the 2300-ELO on-device engine · all four tiers
- Local-Wi-Fi multiplayer · chat and emotes
- Daily curated puzzle · streak tracking
- No account · no telemetry · works offline
Analysis
One-time · unlocks Analyze + Learn
Unlock the in-app Analyze tab and the full Learn track. Pay once, keep forever — no subscription, no server round-trip. Camera scan and host-app extensions stay on Pro.
- Everything in Free
- In-app Analyze tab with engine eval + candidate moves
- Coach Mode · plain-language move explanations
- Full Learn track · openings, endgames, and tactics
- Paste-FEN viewer with PNG export
Pro
3-day free trial
1-week free trial · save 30%
Everything in Analysis plus the on-device vision pipeline. Read any board from your camera or any other app, and analyze positions wherever you find them.
- Everything in Analysis
- Board scanner · camera + screenshot vision pipeline
- Share extension · analyze from any app
- Browser extension · works on every major chess site
- Same engine, same coach — no cloud round-trip
Prices listed in USD · regional pricing applies on the App Store and Google Play
Multiplayer is a library.
Read it. Fork it. Run it.
ChessUp doesn't reinvent the network layer · it sits on top of an open-source mesh transport we maintain in the open with the rest of the StealthOS project.
ConnectionPool
P2P mesh networking library · from StealthOS
ChessUp's local-Wi-Fi multiplayer is built on top of ConnectionPool · the same open-source mesh library that powers pools and games in StealthOS. Local peers connect over the device's native peer transport with DTLS encryption · remote peers via a self-hosted relay with Noise NK and ChaCha20-Poly1305. No matchmaker, no game server, no account.
Your games stay
where they were played.
ChessUp is built so you never have to negotiate with a server about your chess. Four guarantees, baked in.
No account
Open the app and you are in · no email, no sign-up.
No telemetry
Zero analytics, zero tracking, zero third-party SDKs.
On-device
Engine, vision, and coach all run on your phone · nothing uploads.
Local multiplayer · no servers
Peer-to-peer over your Wi-Fi · no matchmaker, no game server.