Your chess
training partner.
4 engines. 8 personalities. ELO 300 to 3500.
Review your games, study openings and practice against engines.
Runs in your browser
4 engines on demand
Engines that fit your needs.
Positional understanding, human-like sparring, a defined style, or raw analysis strength — switch any time.
Komodo Dragon 3.3
When you want to learn positional play.
Slow, calculated, GM-level positional play. Pick Komodo to study the kind of long-term plans that win World Championship games.
Maia 3
When you want a human sparring partner.
Trained on millions of human games. Plays at your target ELO with human-style moves and mistakes. The most realistic practice opponent for any rating.
Rodent IV
When you want a recognizable style.
8 personalities — aggressive sacrificer, defensive crusher, dynamic attacker, classical positional. Pick the style that matches yours and Rodent plays it consistently at any ELO.
Stockfish 18
When you want the objective truth.
The strongest engine in the world. Force depth, multi-PV, tactical brilliance. Pick Stockfish when you want the most accurate evaluation of a position.
Opening theory
3,700+ openings.
Select your repertoire and follow the theory arrows on the board — Chessr helps you learn the book, and what to play when your opponent leaves it.
Build your repertoire
Pick your lines among 3,700+ openings — Italian, Sicilian, London, King's Gambit… seeded with masters win rates.
Theory arrows on the board
The next book move is drawn on the board with the opening's name — step through each line until it leaves theory.
Learn the deviations
When a line leaves the book, Chessr shows the strongest reply so you know what to play next time.
Game review
Game review, without chess.com Diamond.
Same accuracy, same effective Elo, same move classifications — no Diamond membership needed.
- Accuracy % + Effective Elo per player
- Every move classified (best, blunder, brilliant, miss…)
- Per-phase breakdown (opening, middlegame, endgame)
- AI explanations from all chess.com coaches
- Free — no chess.com Diamond required
See the full review
Move-by-move analysis
Start with 5 reviews / day, free.
Standalone Chessr Review Unlocker extension. Free forever for casual use — upgrade to unlimited if you grind.
- Unlimited chess.com game reviews
- Same numbers as Diamond
- No engines — review only
- Works on every finished chess.com game
Free forever · 5 reviews / day · No card required
Upgrade in-extension after install. Cancel anytime · 14-day money-back.
Want the full Chessr (4 engines, analysis board, bot practice)? Chessr Premium →
Everything else
The toolkit around the engine.
Game review, bot practice, opening study — every training tool a serious player wants, in one extension.
Keyboard shortcuts
Step through engine lines and switch settings from the keyboard while you study.
On-board move arrows
Top 3 engine moves rendered as arrows on the analysis board. Glanceable, color-coded by strength.
Live evaluation bar
An eval bar that updates with every move you review. See exactly when the position shifts — and by how much.
Post-game review
A full review of every finished game. Accuracy %, effective Elo, every move classified.
Per-engine personalities
Switch engine + personality any time. Spar against Rodent IV Aggressive, practice with Maia 3 at your level, check lines with Stockfish.
Practice against bots
Train against the computer with engine hints on, and turn every bot game into a lesson.
Opening trainer
12,000+ openings. See when a line leaves known theory and learn the best response.
What 6,743 players are saying
From bullet hunters to FIDE titles — Chessr fits any level, any platform, any style.
Choose your plan
Start free, upgrade when ready. No hidden fees.
Free
Start learning for free
- Komodo Dragon + Stockfish 18 engines
- Engine lines + on-board arrows
- ELO 400-2000
- 2 PersonalitiesEngine: Plays like an engine with minimal errorsAggressive: Attacks relentlessly, prefers active pieces
- Analysis board + evaluation bar
- 5 game reviews / day
- Practice against bots
Premium
Best value - 2 months free
3-day free trial • No card requiredSign up and start your free trial instantly
Everything in Free, plus:
- All 4 engines: Komodo Dragon, Maia 3, Rodent IV, Stockfish 18
- Full ELO range (400-3500)
- All 8 PersonalitiesEngine: Plays like an engine with minimal errorsAggressive: Attacks relentlessly, prefers active piecesDefensive: Emphasizes king safety above allActive: Open positions and well-placed piecesPositional: Solid play and maneuveringEndgame: Prefers promoting pawnsBeginner: Basic mistakes and capturesHuman: Plays like strong human players
- Per-phase game analysis + AI explanations (all chess.com coaches)
- Unlimited chess.com game reviews
- Priority support
Lifetime
Pay once, own forever
Everything in Premium, plus:
- One-time payment
- Lifetime access
- All future updates
Ready to level up your chess?
Install the extension, pick your plan later. Free forever, upgrade anytime.
Get Started with Chessr.ioQuestions? Answers.
Everything you need to know about Chessr — trusted by thousands of players.
What is Chessr and how does it work?
Chessr is a chess training browser extension. 4 engines (Komodo Dragon, Maia 3, Rodent IV, Stockfish 18) power game reviews, the analysis board with evaluation bar, opening study and practice against bots — all from the same Chrome extension.
What's the difference between Chessr Premium and the Review Unlocker?
Chessr Premium is the full extension — 4 engines, analysis board, bot practice, plus game reviews. €3.99/mo, €34.99/year or €79.99 lifetime. Review Unlocker is the standalone lite version on the Chrome Web Store at €1/mo — JUST chess.com game reviews (unlimited), no engine. Different products, different audiences. If you want the full training toolkit, get Premium. If you just want chess.com Diamond reviews for free, get the Unlocker.
What ELO levels are supported?
The full spectrum from 300 (beginner) to 3500 (Stockfish max). Free users get ELO 300-2000, Premium unlocks the full 300-3500 range. The engine adapts to your level. Maia 3 plays in the 800–2600 range like a human opponent, for realistic practice.
What are the 4 engines?
Komodo Dragon 3.3 (positional GM-level play), Maia 3 (trained on real human games, plays naturally at your target rating), Rodent IV with 8 personalities (Aggressive, Defender, Dynamic, Positional, Endgame, Active, Beginner, Engine), and Stockfish 18 (world #1, brute-force max strength). Switch engines any time.
Is there a free trial?
Yes — Premium includes a 3-day free trial. Just link your Discord account, no credit card required. Each user gets one free trial. Cancel anytime, 14-day money-back guarantee on all paid plans.
Does it work on mobile?
Yes — on Android via Kiwi Browser and on iOS via Orion (both support Chrome extensions). On desktop, any Chromium-based browser works: Chrome, Edge, Brave, Arc. Stock iOS Safari and stock Android Chrome don't support extensions, so they're not compatible.
Still have questions?
Ask on Discord