What is the difference between CSV and Parquet?

CSV is a plain-text table format: one row per line, fields separated by commas, usually with a header row. It is the most widely supported data format there is, readable by every spreadsheet, database and analytics tool. Parquet is a columnar binary storage format for analytics. It stores each column separately rather than each row, which makes selective reads fast and compression very effective. It carries a typed schema and underpins most data-lake tooling.

Will I lose anything converting CSV to Parquet?

No. Both formats represent the same data model, so the values and their structure come across intact. Parquet is binary. You cannot inspect it in a text editor — you need a reader.

Anything to watch out for with Parquet?

Parquet is binary. You cannot inspect it in a text editor — you need a reader. Because it is typed, converting from CSV requires inferring types, and inference can guess wrong on sparse or mixed columns.

How is nested data handled?

Parquet represents nesting directly, so the structure of your CSV is preserved as-is.

What should I know about starting from CSV?

CSV has no formal specification, only a convention (RFC 4180). Delimiters, quoting and line endings vary between producers. More broadly: CSV is the lowest common denominator of tabular data: one record per line, fields separated by commas, an optional header row. Every spreadsheet application, database and analytics tool reads it.

When is Parquet the right choice?

Parquet suits: analytical datasets read repeatedly by query engines; archiving large tables where storage cost matters; preserving column types across a pipeline. It is the wrong choice when anything a human needs to open and read directly.

Is there a file size limit?

No hard limit — the constraint is your browser's memory. Files under 50MB convert in a few seconds. Larger files work but take longer, and a browser tab typically has 250-500MB to play with, so very large batches are better split into smaller groups.

Does this work on mobile?

Yes. The drop zone falls back to your phone's file picker, and the conversion runs on-device exactly as it does on desktop. Large files are slower on a phone because there is less CPU and memory available, but nothing about the workflow changes.

Convert CSV to Parquet

Convert CSV to Parquet for columnar storage that is typically 5-10× smaller and far faster to query. Free, in your browser, no upload.

Drop data files to convert

JSON, YAML, XML, CSV, Parquet

Files stay on your device. Open DevTools' Network tab to verify.

Overview

Why convert CSV to Parquet

Parquet is more compact and carries real type information, which CSV does not. Parquet is binary. You cannot inspect it in a text editor — you need a reader.

Comparison

CSV vs Parquet: what actually differs

CSV compared with Parquet across encoding, fidelity, file size and support.
Attribute	CSV	Parquet
Full name	Comma-Separated Values	Apache Parquet
Encoding	Text — editor-readable	Binary
What it preserves	Flat only — no nesting, no types, no formatting	Typed schema preserved; nesting supported
Typical size	Very compact for tabular data	Much smaller than CSV or JSON for the same data — often by 5-10×
Support	Universal. Every spreadsheet, database and BI tool imports it.	Standard in Spark, DuckDB, Pandas, BigQuery, Snowflake and Athena.

How to

How to convert CSV to Parquet

01
Drop your CSV file
Drag one or more CSV files onto the drop zone above, or click to browse. Files stay on your device — there is no upload step. data formats can't be reliably identified from their bytes alone, so the extension is used to work out the source format.
02
Convert to Parquet
convert.now parses the CSV and writes it out as Parquet in a Web Worker, so the page stays responsive even on large files. Nothing is sent anywhere.
03
Download the result
Download the Parquet file, or a zip of all of them for a batch. Filenames are preserved, with the extension changed to .parquet.

Why here

Why convert.now

Private
Files stay in your browser. No upload step. Nothing for anyone to see.
Fast
No queue, no upload wait. Conversion starts the moment you drop a file.
Free
No ads. No file-count limit. No sign-up wall. Just the converter.

FAQ

CSV to Parquet: common questions

No. The CSV to Parquet conversion runs entirely in your browser. Files never leave your device, and there is no server involved in the conversion at all. Open DevTools' Network tab and run a conversion if you want to confirm it — you will see the page and its code load, and no request carrying your file.

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Last updated 27 August 2026

Why convert CSV to Parquet

CSV vs Parquet: what actually differs

How to convert CSV to Parquet

Drop your CSV file

Convert to Parquet

Download the result

Why convert.now

CSV to Parquet: common questions

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