Load
Paste or drop; delimiter (comma, semicolon, tab, pipe) and header row are detected and can be overridden.
Developer
CSV, JSON & JSONL Converter
Tabular data moves between spreadsheets, pandas and training code as CSV, JSON and JSONL. Drop or paste one and get the others, with the delimiter, quoting and header detected, numbers and booleans typed, and a preview of the first rows plus per-column type, null count and distinct count.
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How it works
Check columns
Types and null counts per column; rename or drop columns before converting.
Export
JSON array, JSONL, or CSV with the chosen delimiter and quoting; nested JSON is flattened to dotted columns on the way to CSV.
Formats, limits and the numbers that matter
Type inference
Integers, floats, booleans and ISO dates are recognised; anything with leading zeros or mixed types stays a string. Turn inference off to keep everything as strings.
Encoding
UTF-8 with or without BOM; Excel's semicolon convention in some locales is detected.
Size
Streaming parse handles hundreds of megabytes; the preview shows 500 rows.
Common questions
Excel files?
Save as CSV from Excel first; .xlsx parsing is not included.
Line breaks inside cells?
Handled when the cell is quoted, as the CSV standard requires.
How do I make a text-classification file?
Convert to JSONL with text and label columns, then open it in the Text Classification Labeler.