I play chess casually and usually struggle to figure out why Lichess analysis say my move is a blunder. Almost all the analysis tools will just suggest the best variant for a position, and you will have to follow the suggested engine lines, or play them out manually to analyze it better.

So I built this tool to make that process easier for beginner players. Behind the scene: This app run Stockfish in your browser, at a position, the app will follow the engine's suggested lines, search for any meaningful situation like a check, a fork, a capture, material change, positional disadvantages,... and point that out with an explanation.

You can see the app here: https://whyblunder.vercel.app and paste the PGN of your game.

If you play on Lichess, you can also replace the lichess.org part in the browser URl with https://whyblunder.vercel.app/#<game-id> to quickly analyze, for example: https://whyblunder.vercel.app/#cBVQFX8l