Processed locally — your file never leaves your device
CSV to Parquet Converter
Convert CSV files to compressed Apache Parquet in your browser, using a SQL engine that runs on your own device.
CSV
Drop a spreadsheet or data file hereor click to choose a file from your deviceNothing is uploaded — everything happens on your device.
How it works
- Select or drop a .csv file.
- It's parsed locally and handed to a SQL engine in your browser.
- Download the resulting .parquet file.
Frequently asked questions
- Is my CSV uploaded to generate the Parquet file?
- No. The Parquet file is written on your device by DuckDB compiled to WebAssembly.
- Why convert CSV to Parquet at all?
- Parquet stores data by column and compresses it, so the same dataset is usually far smaller than the CSV and much faster for analytical tools to read. It also records column types, which CSV cannot.
- Are column types detected?
- Yes — the engine infers types from the data rather than storing everything as text, which is most of where the size saving comes from.
- Which tools can read the result?
- Any standard Parquet reader: pandas, Polars, DuckDB, Spark, BigQuery and the Parquet Viewer here.