Convert CSV to Parquet Online — In-Browser, SQL-First

CSV is the lowest common denominator. Parquet is what you actually want once your files get big. PondPilot converts CSV to Parquet entirely in your browser — and lets you clean up the data with SQL on the way.

How to Convert

  1. Open app.pondpilot.io
  2. Drop in your .csv file
  3. Inspect the inferred schema, fix types with SQL if needed
  4. Export as Parquet

The whole pipeline runs locally via DuckDB WebAssembly. Your CSV never leaves your machine.

Why Parquet?

  • Compression — Parquet files are typically 5-20x smaller than the CSV they came from
  • Typed columns — no more guessing whether "007" is a string or an integer
  • Columnar reads — query engines only pay for the columns they touch
  • Portable — Pandas, Polars, DuckDB, Spark, BigQuery, Snowflake, Athena all read it natively

Query First, Then Export

Most converters do a blind one-to-one translation. PondPilot encourages you to shape the data first:

SELECT
  user_id::BIGINT AS user_id,
  TRY_CAST(amount AS DECIMAL(12,2)) AS amount,
  STRPTIME(ts, '%Y-%m-%d %H:%M:%S') AS event_ts,
  lower(trim(country)) AS country
FROM read_csv_auto('raw.csv')
WHERE amount IS NOT NULL

Export the query result as Parquet and you get a clean, well-typed file instead of a faithful copy of a messy CSV.

Handles Big CSVs

DuckDB streams CSV input — it doesn’t have to load the entire file into memory the way a naive script might. Multi-gigabyte CSVs convert comfortably, provided your browser has the RAM for the working set.

Privacy

CSV exports from internal tools routinely contain PII, revenue numbers, and account IDs. PondPilot does everything in-browser. No server, no upload, no log file somewhere with your data in it.

Get Started

Visit app.pondpilot.io and convert your CSV to Parquet in a few clicks.

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