Developer
CSV to JSON Converter
Paste CSV data or open a file and get a clean JSON array instantly, right on your device.
CSV or TSV, up to 10 MB. Values stay as text, including leading zeroes.
Processed on your device — nothing is sent anywhere.
Works in your browser. No account needed.
Frequently asked questions
How are quoted fields and embedded commas handled?
The parser follows the RFC 4180 conventions: fields wrapped in double quotes may contain delimiters, line breaks, and escaped quotes (written as two double quotes). This means exported spreadsheets with commas or newlines inside cells convert correctly without manual cleanup.
What happens if my CSV has no header row?
Turn off the first-row-is-header toggle and each row becomes a plain JSON array of values instead of an object. With the toggle on, the first row supplies the property names and every following row becomes an object keyed by those names.
How do I convert an Excel file to JSON?
Save the sheet as CSV first: in Excel use File → Save As and choose CSV, or in Google Sheets use File → Download → Comma-separated values. Then open that file here or paste its contents. Each sheet must be exported separately, since CSV holds one table at a time.
Can it handle large CSV files?
Files up to 10 MB are accepted. Conversion uses your browser’s memory, so the time it takes depends on the size and shape of the table and your device. Split larger exports into smaller files before opening them.
What happens with duplicate headers or uneven rows?
Duplicate property names would overwrite values in JSON, so conversion stops and asks you to rename the headers or switch to arrays. Rows with more values than headers also show an error instead of losing cells. Missing trailing values become empty strings. A UTF-8 byte-order mark is removed from the start of the file, and values such as 007 stay strings.
Is my data uploaded anywhere?
No. The conversion runs entirely in your browser using JavaScript, so the CSV never leaves your device. You can even use the tool offline once the page has loaded.
About this tool
This converter turns CSV data into a clean, pretty-printed JSON array. Paste rows straight from a spreadsheet or open a .csv file, and the output appears instantly: with a header row, each line becomes a JSON object keyed by the column names; without one, each line becomes an array of values. For example, id,name followed by 007,Ada produces an object with the strings "007" and "Ada"; the leading zeroes remain intact. Copy the result to your clipboard or download it as a .json file.
Parsing happens entirely on your device with JavaScript. The parser follows RFC 4180 conventions, so quoted fields containing commas, line breaks or escaped quotes — the cases that break naive split-on-comma scripts — come through intact. Delimiter detection recognizes commas, semicolons and tabs automatically, and you can override the choice manually when a file is ambiguous. Malformed quoted fields produce an error, and duplicate headers or extra cells stop conversion so you can correct the table before exporting.
It is an everyday tool for developers seeding a database or API fixture from a spreadsheet, analysts moving data from Excel into a JavaScript charting library, and anyone writing a quick script that is easier to feed with JSON than with CSV. Because the output is standard JSON, it drops directly into fetch mocks, configuration files and unit tests.
Two tips save time. Check the header toggle first — the most common surprise output, an array of arrays instead of objects, simply means the first-row-is-header switch is off. And if numbers arrive as strings, that is normal: CSV has no types, so every value is text. Convert them in your own code afterwards, where you control which columns really are numeric.