How are commas inside a field handled?

Correctly, as long as the field is quoted. A value wrapped in double quotes may contain commas, line breaks and escaped double quotes, and the parser respects that rather than splitting blindly. Converting back to CSV re-adds quoting wherever a value needs it.

Are numbers converted to real JSON numbers?

Only if you turn on type inference. With it off, every cell stays a string, which is the safer default: it prevents an identifier like a zip code or an order number from losing its leading zeros, and stops long numeric ids from being reformatted.

No. Parsing happens in your browser and no request is made, so exports containing customer records or internal data are never transmitted. Nothing persists after you close the page.

What happens to records with different keys?

When converting JSON to CSV the header is the union of every key across all records, and any record missing a key gets an empty cell there. That keeps columns aligned instead of producing rows of differing width.

Encoding & conversion

CSV to JSON Converter (and Back)

Turn CSV rows into JSON objects, or flatten JSON back to CSV.

Direction

Delimiter

Infer types

Off keeps every cell a string, which protects leading zeros.

CSV input

CSV to convert

JSON output

About this tool

CSV is what you get out of a spreadsheet, a database export, or an analytics report. JSON is what most code wants to consume. Converting between the two is one of those chores that appears whenever data crosses from a human-facing tool into a programmatic one.

Going CSV to JSON, the first row is treated as the header and each subsequent row becomes an object keyed by those column names. That is the shape you want for seeding a test fixture, feeding an API, or loading records into a script. Going the other way, an array of objects is flattened back into rows, with the union of all keys as the header so records with missing fields still line up in the right columns.

The awkward part of CSV is quoting, and it is where naive splitting on commas falls apart. A field can legitimately contain a comma, a double quote, or a line break, as long as it is wrapped in quotes with internal quotes doubled. A parser that ignores this will silently shift every column after the first quoted comma, which is the kind of bug that looks like bad data rather than bad parsing. This tool implements the quoting rules properly in both directions, so values containing separators survive a round trip.

You can pick the delimiter, since tab-separated and semicolon-separated exports are common, the latter especially from spreadsheets in locales where the comma is the decimal separator. Optional type inference will turn numeric and boolean-looking cells into real JSON numbers and booleans instead of leaving everything as strings.

How to use it

Choose CSV to JSON, or JSON to CSV.
Set the delimiter if your data is not comma-separated.
Paste your data into the input panel.
Copy the converted output.

Frequently asked questions

How are commas inside a field handled?: Correctly, as long as the field is quoted. A value wrapped in double quotes may contain commas, line breaks and escaped double quotes, and the parser respects that rather than splitting blindly. Converting back to CSV re-adds quoting wherever a value needs it.
Are numbers converted to real JSON numbers?: Only if you turn on type inference. With it off, every cell stays a string, which is the safer default: it prevents an identifier like a zip code or an order number from losing its leading zeros, and stops long numeric ids from being reformatted.
Is my data uploaded?: No. Parsing happens in your browser and no request is made, so exports containing customer records or internal data are never transmitted. Nothing persists after you close the page.
What happens to records with different keys?: When converting JSON to CSV the header is the union of every key across all records, and any record missing a key gets an empty cell there. That keeps columns aligned instead of producing rows of differing width.