Everyone said this was impossible.

ClickHouse is a massive multi-threaded engine. Porting it to WebAssembly — a single-threaded runtime — was supposed to be a non-starter. Every AI we asked told us the same thing: can't be done.

But years of working on this engine gave me a different intuition. From first principles, there was no fundamental barrier. Just a hard problem that everyone had assumed away.

So we pointed AI at it — refactor, regress, repeat — instead of taking "impossible" for an answer.

The result: http://wasm.chdb.io

A full ClickHouse OLAP engine, running entirely in your browser tab. No server. Query local files and S3 Parquet in-process.

Huge thanks to @wudidapaopao for the relentless work that made it real.