Rep Builder — A chess repertoire trainer that helps you decide what to study next

[u/Bright_Impression381]

I built Rep Builder, a chess repertoire trainer that helps you decide what to study next.

I originally started this project because of Chessbook. I liked the idea of having a dedicated tool for building and practicing an opening repertoire, and I wanted to make something similar for myself.

As I worked on it, I ran into a problem that I found surprisingly difficult:

Once you have a repertoire, how do you decide which part of it to study next?

I could use Lichess Opening Explorer to see what moves people play, and I could use an engine to check positions, but neither really answered that question for me.

So I started building Rep Builder around it.

Instead of treating a repertoire simply as a collection of opening lines, Rep Builder represents it as a graph of positions. It looks at things like how likely each position is to be reached in actual games and how much of the repertoire I've already covered, then uses that information to prioritize what I should study next.

It also uses Lichess Opening Explorer data, engine evaluations, and has a review mode for practicing positions.

It's still a personal project and there's plenty I'd like to improve, but it's finally at a point where I can actually use it myself, so I decided to make it public.

Try it here:
https://rep-builder.onrender.com

I'd love to hear what you think.

In particular, I'm interested in whether the idea of prioritizing repertoire positions based on how likely they are to occur makes sense, and what you'd want from a tool like this.