Convert CSV to Parquet Online

Large CSV Viewer converts CSV files to Apache Parquet format directly from your browser. Upload your CSV, optionally filter the rows you want, then choose Export → Parquet from the File menu. The conversion is powered by DuckDB and handles files of any size. Free, no account required.

Last updated:

Convert any CSV file to Parquet format online for free. Fast columnar conversion powered by DuckDB. No install, no account, no row limits.

Apache Parquet is the standard columnar storage format for big data pipelines, data lakes, and analytics tools like Spark, Pandas, and BigQuery. Large CSV Viewer converts any CSV file to Parquet in one click — powered by DuckDB, which natively reads and writes the Parquet format.

Key features

  • One-click CSV to Parquet conversion
  • Powered by DuckDB — the same engine used in production data pipelines
  • Data types are inferred and preserved in the Parquet schema
  • Filter rows before converting to reduce output file size

How it works

  1. Upload your CSV file. Drop your CSV into the viewer. Your data appears immediately for preview.
  2. Filter (optional). Apply column filters or search to include only the rows you need in the Parquet output.
  3. Export as Parquet. Open the File menu and choose 'Export as Parquet'. A .parquet file downloads immediately, ready to use in Spark, Pandas, DuckDB, or BigQuery.

Ready to try it?

Free, instant — no account or install needed.

Open CSV Viewer →

Frequently asked questions

What is Parquet format?

Apache Parquet is a columnar storage format designed for efficient analytics. It compresses data significantly compared to CSV and is the standard format for tools like Apache Spark, Pandas, BigQuery, and Snowflake.

Why convert CSV to Parquet?

Parquet files are typically 5–10x smaller than equivalent CSV files and 10–100x faster to query in analytics tools. If you're loading data into a data lake or running queries with Spark or BigQuery, Parquet is the preferred format.

How does the conversion work?

DuckDB reads your CSV, infers column data types, and writes a properly typed Parquet file. Numeric columns become integer or float types; dates become date types — not strings.

Can I convert a large CSV to Parquet?

Yes. The conversion runs server-side using DuckDB with no row limits.

Is the CSV to Parquet conversion free?

Yes, completely free. No account, no size limit, no paywall.