Data converter · runs 100% in your browser
JSON to Parquet Converter
Convert JSON files to Parquet in your browser via DuckDB-Wasm — the same SQL engine the data community uses, compiled to WebAssembly. The first conversion of your session loads the engine (~30 MB, cached afterwards); subsequent conversions are fast.
How to use
- Drop your JSON file.
- DuckDB-Wasm parses it locally with read_json_auto.
- Output is materialised as Parquet in browser memory.
- Click Download.
FAQ
What about column types?
Schema is preserved: JSON types map to their Parquet equivalents. Numeric, string, boolean, timestamp, and nested types all carry over.
Does my data file upload to a server?
No. Conversion runs entirely in your browser using WebAssembly and Web APIs. Open the Network tab in DevTools while you convert — you'll see no outbound traffic carrying your file.
Is this really free?
Yes. No signup, no quota, no upgrade tier. The conversion runs on your machine, so it costs us nothing to host.
Is there a file size limit?
Browser memory is the only ceiling. On a modern desktop browser, a few hundred megabytes works fine. Mobile devices have tighter limits.