Grammarly, but for code. I liked how Grammarly explains why something is wrong instead of just silently fixing it, and wanted to bring that idea to programming.

It analyzes your code as you type and color-codes issues inline: red for errors, yellow for warnings, and blue for suggestions. Clicking on one shows you why it’s wrong and how to fix it. Code runs in a sandbox across nine languages.

Frontend with React and Monaco, with FastAPI and Gemini on the backend and Postgres for storing history. The hardest part was keeping the AI analysis running constantly without making the editor feel slow or laggy.