JSON files

Polars can read and write both standard JSON and newline-delimited JSON (NDJSON).

Read

JSON

Reading a JSON file should look familiar:

{{code_block('user-guide/io/json','read',['read_json'])}}

Newline Delimited JSON

JSON objects that are delimited by newlines can be read into Polars in a much more performant way than standard json.

Polars can read an NDJSON file into a DataFrame using the read_ndjson function:

{{code_block('user-guide/io/json','readnd',['read_ndjson'])}}

Write

{{code_block('user-guide/io/json','write',['write_json','write_ndjson'])}}

Scan

Polars allows you to scan a JSON input only for newline delimited json. Scanning delays the actual parsing of the file and instead returns a lazy computation holder called a LazyFrame.

{{code_block('user-guide/io/json','scan',['scan_ndjson'])}}