Simon Willison Ships an SQLite Query Explainer That Runs Python in Pyodide/WASM and Annotates Query Plans in Plain English

Simon Willison·medium signal

Prompted by Julia Evans' July 17 admission that she still can't read query plans, Willison had Fable build a browser-only tool that runs arbitrary SQL against a SQLite database and renders both EXPLAIN QUERY PLAN output and the lower-level EXPLAIN bytecode with per-line plain-English annotations. The whole thing executes client-side via SQLite-in-Python compiled to WebAssembly through Pyodide — no server. Willison explicitly flags that he isn't expert enough to fully verify the annotations, which is the honest caveat most AI-built dev tools skip.