What is D4 Chess Club and who is it for?+−
D4 Chess Club™ (d4chess.club) is a web-based chess training platform for club players (roughly 800–2000). It combines Stockfish analysis, an AI Socratic coach, theme puzzles, Opening Explorer, and courses into one free-to-start app focused on fixing your weaknesses — not just playing games.
Is D4Chess free to use?+−
Yes. Free forever includes: play vs computer (1000–3200 Elo), Opening Explorer (3,700+), Stockfish analysis, threat overlay, 5 puzzles/day, Chess Basics, leaderboard/events, and 3 AI coaching sessions per month. No credit card required. Premium is $5.99/month.
What is the difference between Free and Premium?+−
Premium adds: unlimited AI coaching, voice feedback, full AI Walkthrough, unlimited puzzles, weakness targeting into recommended theme drills, Tactics 101, Opening Principles, and future courses when they ship. Personalized/My Drills from your own game positions, spaced repetition (SM-2), and the Opening Repertoire Trainer are on the roadmap — not included as live Premium today.
How does the AI chess coach work?+−
The coach uses the Socratic method: targeted questions that guide you to find the idea yourself, grounded in verified Stockfish analysis. Free accounts get 3 sessions per month; Premium is unlimited.
What is the AI Walkthrough?+−
Regular Stockfish analysis (Free) classifies every move. The AI Walkthrough (Premium) adds personalized explanations on key moments, punishment lines, and natural-language follow-ups.
Does D4Chess have an opening trainer?+−
Live: Opening Explorer and opening recognition (ECO codes) in analysis, plus Opening Principles (Premium course). Roadmap: Opening Repertoire Trainer to drill your personal lines from memory. Explorer is not the repertoire trainer.
How do puzzles and spaced repetition work?+−
Theme puzzles cover forks, pins, skewers, and more. Free: 5/day. Premium: unlimited. Weakness targeting routes you to themes from your games. Spaced repetition (SM-2) is on the roadmap — we do not claim it as live.
How does weakness targeting work?+−
Games are tagged by mistake patterns. Recommended Drills after review route you to matching puzzle themes. Custom My Drills built from your exact game positions are still on the roadmap.
How does Stockfish analysis work?+−
Full analysis runs Stockfish 18 on the backend. Moves are classified by centipawn loss. Offline browser Stockfish is not how full analysis works.
Can I import games from Chess.com or Lichess?+−
Yes — paste PGN, upload a PGN file, or use username import. Board Scanner can open a photographed position as FEN for exploration or a coach session.
What does Premium cost? Is there an annual plan?+−
Premium is $5.99 per month. There is no annual plan currently — the subscription renews monthly. Cancel anytime; 7-day money-back on first payment.
Can D4Chess help me stop blundering?+−
That is the core use case: threat overlay during review, Socratic explanations of missed threats, and theme drills for those patterns. We do not invent Elo or blunder-rate guarantees — improvement depends on consistent practice.
Is there a mobile app?+−
D4Chess is an installable PWA (Add to Home Screen). Dedicated native iOS/Android apps are on the roadmap.
Who built D4Chess?+−
Haven Command LLC. Product: d4chess.club. Business: havencommand.com.