This tool is new and 100% a work in progress. Don't expect perfection. Feedback is appreciated.
The short answer: I wanted to build one that has everything I could possibly ever want. Making my own means I can implement some cool ideas that others just don't have, e.g. self-specified daily goals, a consistency measure reflecting how reliably you have been meeting your goal, a "Daily Routine" feature, a powerful and customizable open-ended mode, and more to come.
Kaizen (改善) is a Japanese concept meaning "continuous improvement through small, consistent steps." (to any Japanese person reading this: Please contact me this is inaccurate or could be described better!) The idea here is simple: set a realistic daily goal, follow through with it, and let the rating system give you honest feedback over time.
Players of any strength. Beginners can start with Mate in 1 or 2 and a modest daily goal; experienced players can enable adaptive difficulty and use the consistency score to maintain discipline in the long term.
Puzzles come from a large open-source database of positions derived from real games (the mighty lichess puzzle database!). Each position has a pre-computed rating so the trainer can serve you puzzles at the right difficulty, regardless of whether you choose a fixed range or let the system adapt.
Puzzles you have already attempted are excluded from future draws, so you will encounter fresh positions every session. Once the pool of unseen puzzles at your target range thins out, the trainer widens the search window gradually before eventually allowing repeats.
Your puzzle rating is maintained using the Glicko-2 algorithm — the same system used by Lichess and FIDE for online ratings. It tracks not just your current rating but also a rating deviation (RD) that reflects how confident the system is in the estimate.
A high RD means the system is uncertain about your true strength and will update your rating more aggressively after each attempt. As you solve more puzzles, RD decreases and your rating stabilises. Periods of inactivity cause RD to rise again — the system acknowledges that it has less information about where you stand.
Two modes are available from the settings panel:
You can also filter by theme (pin, fork, endgame, etc.) independently of the difficulty mode.
A routine is a named sequence of puzzle sections that resets every day at midnight. Each section has its own difficulty range, theme filter, and puzzle count. Sections are meant to be completed in order, and the puzzle set for a given day is deterministic — two players running the same routine on the same date face identical positions.
This makes routines useful for group training, for example. A team or study group can all attempt the same positions and compare their times and mistake counts on the routine's leaderboard.
The Daily Checkmate Ladder is a five-section routine included for everyone. It covers mate-in-1 through mate-in-5, stepping up in difficulty through each section. It's a quick daily warm-up and a good benchmark for tactical sharpness.
Pro users can create custom routines and share them with the community. A routine can have up to ten sections with any combination of difficulty ranges and themes. Once published, other logged-in users can run it and appear on its leaderboard.
The consistency score (0–100) captures how reliably you hit your chosen daily puzzle goal. It is intentionally independent of accuracy — a day on which you attempt your target number of puzzles counts fully, regardless of how many you solved. The idea is to separate two distinct habits: showing up (consistency) and performing well (rating).
You set your own daily goal between 3 and 100 puzzles. Once set, it can be adjusted every five days, and changes only affect future days — past history is frozen at the goal that was active on each day. This prevents retroactive gaming of the score.
Until you set a goal, your consistency appears as "?" on your profile and on the leaderboard. Goal-setting and tracking are available to all logged-in users.
Each calendar day, you earn a credit between 0 and 1: the number of attempts divided by your goal for that day, capped at 1. Missing a day earns 0.
The score is the product of two terms:
I am IM Jakob Pfreundt. In 2025 I started building my first chess-related tool, ChessMint. That one is more geared toward coaches as well as players who prefer to train offline and/or off-screen. You could say Kaizen64 is the natural counterpart, trying to make online training as fun and effective as possible.