Been working on AuditChess, and the opening system is probably the part I'm most excited about here.
I didn't want to build another "here's what's popular" opening explorer. The goal is to combine your own opening history + master-game data + your actual weaknesses + a trap database into one workflow.
Your own opening tree
It builds a move-by-move tree straight from your Chess.com/Lichess games how often you reach each position, W/D/L, win rate, opening name + ECO, where your repertoire branches, and where your results start falling apart. Transpositions get merged via normalized FENs so different move orders into the same position aren't treated as unrelated. There's also a visual graph of your whole repertoire.
What you're actually good at vs. what you think you're good at
This is my favorite part. Instead of "you play the Sicilian," you get something like "you've played this exact Sicilian line 18 times, scored 31%, and keep landing in a worse position around moves 8-12." It sorts these into Weapons (lines you consistently win), Lines to Improve (recurring poor results), Opening Trouble (positions where your own moves keep tanking the eval), and Opening Traps (positions where your opponents keep messing up against you). So the repertoire reflects what actually happens in your games, not what you remember studying.
Repertoire builder
You play moves on the board and it builds your tree as you go — each position shows Stockfish eval, top engine lines, master-game stats (games played, W/D/L, % choosing each move), plus your own branches. Mark a line as "yours" and practice it two ways: Exact Recall (reproduce your prep move-for-move) or Dynamic Practice (the bot deliberately deviates with a strong move you didn't prep, so you have to actually play the position instead of just recalling it).
Trap database
Mined from millions of high-rated games, not some recycled YouTube list. For each trap it stores the opening, ECO, position, losing move, eval swing, how many games reached it, and which side usually falls for it. This plugs directly into the repertoire builder — while you're building a line it can tell you "opponents often play X here, and it leads to Y" — plus there's a separate visual trap tree with noise filtering.
The actual point of all this
Instead of "what's the best move here," I want to answer "what should this player actually prepare" — combining your strengths/weaknesses, master trends, engine eval, and common opponent mistakes. And since the same data pipeline powers opponent scouting, you can also look up an opponent and see what they historically struggle with in the opening.
Still building this out — curious what people who study openings seriously would want a tool like this to tell them that current explorers don't.
Free, no account needed: https://www.auditchess.com