CSV to JSON Lines converter

CSV rows are normalised by our table engine before JSON Lines is written, preserving row order and typed values for csv-to-jsonl.

Converted with Table engine · nothing stored
Free: 5 conversions a day · 5 MB each
Higher limits →

What changes

CSV rows are normalised by our table engine before JSON Lines is written, preserving row order and typed values for csv-to-jsonl.
Nested CSV values use flattened column names, while JSONL receives arrays according to the arrayMode setting.
The converter treats the file as one logical table, so comments, prose around tables, and source metadata are skipped.
Numbers, booleans, dates, blanks, and strings are inferred and then serialized in the destination format's native shape.
Delimiter, encoding, newline, and header choices apply only where CSV or JSONL is a text table.
The JSONL result focuses on portable data, not formulas, rich layout, or application-specific metadata.

A real CSV → JSON Lines run

We converted our CSV sample (226 B) with Table engine on 2026-09-11. It took 1 ms and produced a 467 B JSON Lines file, 2.1× larger than the input. The engine raised no warnings.

Input · sample.csv · 226 B

4 data rows × 5 columns; header: company,stage,arr,owner,close_date

Rows: 4
Columns: 5
Header: company,stage,arr,owner,close_date

Output · sample.jsonl · 467 B

4 JSON objects, one per line; keys: company, stage, arr, owner, close_date

Records: 4
Keys: company, stage, arr, owner, close_date

First lines of the output

jsonl

{"company":"Northwind Traders","stage":"Proposal","arr":48000,"owner":"R. Ayers","close_date":"2026-10-14T00:00:00.000Z"}
{"company":"Contoso Ltd","stage":"Negotiation","arr":120000,"owner":"P. Ng","close_date":"2026-09-30T00:00:00.000Z"}
{"company":"Fabrikam","stage":"Qualified","arr":22500,"owner":"R. Ayers","close_date":"2026-11-02T00:00:00.000Z"}
{"company":"Tailspin Toys","stage":"Won","arr":64000,"owner":"M. Okafor","close_date":"2026-09-03T00:00:00.000Z"}

Options

delimiter: Choose comma, tab, pipe, semicolon, or another separator for delimited text input or output.
header: Treat the first delimited row as field names instead of generated column labels.
quote: Set the quote character used when parsing CSV, TSV, or TXT fields.
encoding: Decode UTF-8 or Latin-1 text before parsing table-oriented formats.

Example

input

name,score
Ada,9
Bo,7

output

{"name":"Ada","score":9}
{"name":"Bo","score":7}

Do it in code

python

import pandas as pd
df = pd.read_csv("input.csv")
df.to_json("output.jsonl", orient="records", lines=True)

CSV to JSON Lines by API or MCP

The HTTP API and the MCP server run the exact engine this page uses (Table engine); the response carries the same warnings the web converter shows. Check support first with GET /api/v1/pairs?from=csv&to=jsonl.

curl

curl -X POST https://filetypeconverters.com/api/v1/convert \
  -H "Authorization: Bearer $FTC_API_KEY" \
  -F "file=@input.csv" -F "from=csv" -F "to=jsonl" \
  -F 'options={"delimiter":","}' \
  --output output.jsonl

Options this engine accepts for CSV → JSON Lines

Key	Applies to	Type	Default
delimiter	Reading CSV	string	,
header	Reading CSV	boolean	true
quote	Reading CSV	string	"
encoding	Reading CSV	utf-8 · latin1	utf-8
delimiter	Writing JSON Lines	string	,
newline	Writing JSON Lines	·
sheetName	Writing JSON Lines	string
dialect	Writing JSON Lines	postgres · mysql · sqlite	postgres
tableName	Writing JSON Lines	string	data
createTable	Writing JSON Lines	boolean	true

API reference

Related conversions

This converter works today; a tested write-up of what changes for CSV → JSON Lines is in progress.