CSV to Parquet Converter
Handle Million-Row Files in Your Browser

Convert CSV files to Apache Parquet format instantly in your browser. Handles million-row files with zero upload.

Drag & drop your file here, or browse

Accepts: .csv (up to 500 MB)

Your data stays in your browser. By using this tool, you agree to our Terms and Privacy Policy.

How to Convert CSV to Parquet (Large File Support)

Drag and drop your CSV file onto the drop zone at the top of the page, or click to browse and select a file.

Conversion starts automatically and a preview of the schema and data is displayed.

Click the "Download Parquet" button to save the converted result.

Key Features of This CSV to Parquet Converter

100% Local Processing: Your files are never uploaded to a server. All conversion happens in your browser using WebAssembly, so your sensitive data stays private.
3-10x Smaller Files: Apache Parquet uses columnar storage and efficient compression to dramatically reduce file sizes compared to CSV, making storage and transfer faster.
Free with No Limits: No row limits, no file count restrictions, and no account required. Start converting right away.

CSV vs Parquet: Differences and Benefits of Converting

CSV is a simple text-based tabular format. Apache Parquet is a columnar binary format optimized for analytics, with built-in compression and type preservation.

	CSV	Parquet
Storage	Row-based text	Columnar binary
File size	Large (no compression)	3-10x smaller (compressed)
Data types	Everything is a string	Integer, Float, Date, Boolean, etc.
Read speed	Must scan entire file	Column pruning + predicate pushdown
Common use	Data exchange, Excel	Data lakes, Spark, BigQuery, DuckDB

Benefits of Converting CSV to Parquet

Drastically reduce storage costs with 3-10x compression
Preserve data types (integers, dates, booleans) — no more parsing strings
Enable faster queries in analytics tools like DuckDB, Spark, and BigQuery

Frequently Asked Questions

Is my data uploaded to a server?

No. Your file never leaves your browser. All processing happens locally using WebAssembly.

Is it free?

Yes, this tool is completely free with no row limits.

Can I convert a large CSV with millions of rows to Parquet?

Yes. This tool uses DuckDB-WASM to process files entirely in your browser. It handles millions of rows and the Parquet output is typically 3-10x smaller than the original CSV.

Does the tool handle different text encodings (prevent garbled text)?

Yes. Our tool automatically detects and converts most global text encodings on the fly. We fully support UTF-8, UTF-16, Windows-1252, ISO-8859-1 (Latin-1), and various other international formats.

What compression is used?

The output uses Snappy compression, which offers a good balance of compression ratio and speed. Snappy is widely supported by Spark, BigQuery, DuckDB, and other analytics tools.

What is the file size limit?

The input limit is 500MB. Since Parquet output is typically 3-10x smaller than CSV, the resulting file will be well within browser memory limits.

Can I clean up or filter data before converting?

This page is a dedicated conversion tool. For data cleansing before conversion, try LeapRows — no sign-up required.

What browsers are supported?

Any modern browser with WebAssembly support: Chrome, Firefox, Edge, Safari (14+).