CSV to Parquet Converter — Columnar Format Tool
Convert CSV files to Apache Parquet format instantly in your browser. Automatic type inference, Snappy compression, no uploads required.
How to Use CSV to Parquet Converter — Columnar Format Tool
How to Use CSV to Parquet Converter
What is Apache Parquet?
Apache Parquet is a columnar storage format widely used in data engineering and analytics. Compared to CSV, Parquet offers:
- Smaller file sizes — typically 2–10x smaller due to columnar encoding and compression
- Faster queries — column pruning means only relevant columns are read
- Type safety — explicit schema with typed columns
- Wide ecosystem support — Spark, Flink, BigQuery, Redshift, DuckDB, Pandas, and more
Step 1: Upload Your CSV File
Click the upload area or drag and drop your .csv file. The first row must contain column headers. Maximum file size: 50MB.
Step 2: Convert
Click "Convert to Parquet". The tool:
- Parses the CSV (handles quoted values, commas in fields)
- Infers the column type for each column (BOOLEAN, INT32, INT64, DOUBLE, or STRING)
- Writes a Parquet file with Snappy compression
Step 3: Download
Click "Download Parquet" to save the .parquet file. The output uses the same base name as the input.
Type Inference
The converter automatically detects column types:
true/falsevalues → BOOLEAN- Whole numbers fitting 32-bit range → INT32
- Whole numbers outside 32-bit range → INT64
- Decimal numbers → DOUBLE
- Everything else → STRING
Tips
- Ensure your CSV has a header row as the first line
- Empty cells in numeric columns are stored as null
- For large datasets (10MB+), processing may take a few seconds
- The output Parquet file uses Snappy compression by default
- All processing is offline after page load — no internet required
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