CSV to JSON 100% local
Everything runs in your browser. Files never leave your device.
CSV input
Paste CSV or open a .csv file
JSON output
Converted JSON
Ready
0
documents converted worldwide Your files never leave your browser. Only an anonymous +1 is counted, never your documents.

CSV to JSON converter

Convert CSV to JSON locally in your browser.

MarkDone turns CSV exports from spreadsheets, databases, and analytics tools into clean JSON arrays for APIs, config files, and code. It auto-detects the delimiter, handles quoted fields and embedded newlines, and optionally infers numbers and booleans — all on your device, so your data is never uploaded.

Smart parsingHandles quoted fields, embedded commas and newlines, and escaped quotes correctly.
Type inferenceOptionally turns 42, true, and null into real JSON types instead of strings.
Private by designSpreadsheets and exports never leave your browser.
All MarkDone converters JSON to CSV converter JSON to YAML converter JSON to TOON converter

How to convert CSV to JSON

  1. Paste CSV or open a .csv / .tsv file.
  2. Pick the delimiter or let MarkDone auto-detect it.
  3. Copy or download the JSON for your API, config, or code.

From spreadsheet to API payload

CSV is everywhere — exports, reports, database dumps — but most code and APIs want JSON. Convert once and paste a clean array of objects straight into your request body, fixture file, or seed script.

Correct, not just quick

A comma inside a quoted field shouldn’t break a row. MarkDone follows RFC 4180 parsing rules so values like "Doe, John" stay intact, then validates structure before showing the JSON.

Is my CSV uploaded when I convert it to JSON?

No. CSV to JSON conversion runs entirely in your browser. Your spreadsheet data and exports stay on your device.

Which delimiters are supported?

Comma, semicolon, tab, and pipe. MarkDone auto-detects the delimiter by default, which is handy for European CSVs that use semicolons, and you can override it manually.

Does it convert numbers and booleans automatically?

Yes, when "Infer numbers/booleans" is on, values like 42, 3.14, true, false, and null become real JSON types. Turn it off to keep every value as a string.

What if the first row is not a header?

Uncheck "First row is header" and MarkDone outputs an array of arrays instead of an array of objects.

Can I convert JSON back to CSV?

Yes. Switch direction with one click, or use the dedicated JSON to CSV converter.