JSON to Parquet converter

Convert JSON or NDJSON files to Apache Parquet in your browser. Choose a compression codec and download the result locally.

How the JSON to Parquet conversion works

Drop a .json (array of objects), .ndjson, or .jsonl file. It is parsed locally, column types are inferred, and after a preview you download a typed .parquet with your chosen codec. Objects with different keys merge into one schema with nulls where a key is absent.

How types are inferred

• true/false → BOOLEAN
• integers within ±2.1B → INT32, larger → INT64
• decimals → DOUBLE
• ISO 8601 strings → TIMESTAMP
• mixed/other → STRING
• Sampling covers the first 200 values per column; mixed columns fall back to STRING.

Large files

For hundreds of MB and up: pandas read_json(lines=True).to_parquet() or DuckDB read_json_auto with COPY … TO FORMAT PARQUET.