CSV to JSON Converter

How to convert CSV to JSON

A CSV export can look correct in a spreadsheet but still produce the wrong JSON when its separator or header row differs from the expected format. For example, a semicolon separated file can place every value in one field if it is read as comma separated data.

You can choose the matching Value Separator, keep First row is header on when the first line contains column names, and review the preview before saving. This works because the parser can assign each value to the intended key before JSON is created.

1. You can add CSV data Paste comma separated values or upload a .csv file. The preview shows whether rows and columns were read correctly.
2. You can choose the JSON shape Array Format creates one object per row, which suits most APIs and scripts. Turn it off for a column oriented object, and use Detect numbers & booleans when typed values are useful.
3. Save the result Check the JSON, then copy it or download data.json. The conversion runs in this browser, so the input is not sent to a server.

CSV and JSON formats

What is CSV?

A CSV file represents a table as lines of fields separated by commas, semicolons, tabs, or pipes. For example, Name,Age followed by Ada,36 stores two columns without formulas or visual styling.

You can set the separator to match the source file because a parser cannot reliably split fields with the wrong delimiter.

What is JSON?

JSON stores values in objects with named keys, and an array of objects represents multiple records. A header row such as Name,Age becomes keys such as "Name" and "Age", so each row can be read by an API or script.

CSV to JSON example

A two row CSV table becomes a JSON array when Array Format is enabled. The shared headers become object keys, which keeps the output easy to inspect and use.

Name,Age,City
Ada,36,London
Lin,29,Taipei

[
  {"Name": "Ada", "Age": 36, "City": "London"},
  {"Name": "Lin", "Age": 29, "City": "Taipei"}
]

Common CSV to JSON problems

Quoted commas inside fields

A name such as "Doe, Jane" contains a comma but still represents one CSV field. Keep the quotation marks because the parser uses them to preserve the value as one JSON string.

Leading zeros

A quoted value such as "00123" keeps its zeros during conversion, while a spreadsheet program may display it as a number later. Keep identifiers quoted when their zeros carry meaning.

Everything appears in one column

This usually means the file uses semicolons or tabs instead of commas. Select the matching Value Separator because the parser then finds the intended fields.

Unexpected character encoding

Accented characters can look wrong when a source file is saved with an older encoding. Use UTF 8 input when available because it represents a broad range of characters consistently.

CSV to JSON in code

A script can produce the same array of objects when the conversion must run as part of a data workflow. These examples use standard parsing patterns, so the CSV still needs a correct delimiter and header row.

import csv, json
with open("data.csv", newline="") as f:
    print(json.dumps(list(csv.DictReader(f)), indent=2))

const rows = csvText.trim().split(/
/).map(l => l.split(","));
const headers = rows.shift();
const json = rows.map(r => Object.fromEntries(headers.map((h,i) => [h, r[i]])));