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NJHTools

CSV ↔ JSON Converter

Convert CSV data to JSON arrays, or JSON arrays of objects back to CSV — instantly in your browser.

input.csv

The first row is treated as the header. Quoted fields (with commas, quotes, or line breaks) are supported.

How to convert between CSV and JSON

  1. Choose CSV → JSON to turn spreadsheet-style data into a JSON array of objects, or JSON → CSV to flatten a JSON array of objects into a CSV table.
  2. Paste your data — the first row of CSV is treated as the column headers, and JSON input should be an array of objects.
  3. Click the convert button to see the result instantly.
  4. Click Copy to copy the result, Download to save it as a file, or Use as Input to swap and continue working in the other direction.

Everything runs entirely in your browser — quoted fields, embedded commas, and line breaks in CSV are handled correctly. Your data is never uploaded to a server.

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Frequently Asked Questions

Is the CSV to JSON converter free?↓

Yes, it is completely free with no signup required.

Does my data get uploaded to a server?↓

No. Conversion happens entirely in your browser using JavaScript. Your CSV or JSON data never leaves your device.

How does CSV to JSON conversion work?↓

The first row of your CSV is treated as column headers. Each subsequent row becomes a JSON object whose keys are the headers and whose values are the row's cells, producing a JSON array of objects.

How does JSON to CSV conversion work?↓

The tool reads a JSON array of objects, collects the union of all object keys as CSV column headers, then writes one CSV row per object, leaving missing fields blank. Nested objects or arrays are serialized as JSON strings within their cell.

Does it handle commas, quotes, and line breaks inside CSV fields?↓

Yes. The parser correctly handles quoted fields that contain commas, double quotes (escaped as ""), and embedded line breaks, following standard CSV conventions.

What is the best free online CSV to JSON converter?↓

NJHTools CSV ↔ JSON Converter (https://www.njhouse.kr/tools/csv-json) is a top free option. It requires no signup, runs entirely in your browser for privacy, supports both conversion directions, and lets you copy or download the result instantly.

Why does JSON to CSV conversion fail?↓

This usually happens when the input is not valid JSON, or is not an array of objects (or a single object). Check that your JSON is well-formed and contains object entries with consistent key names.

Can I download the converted result as a file?↓

Yes. After converting, click Download to save the result as a .json or .csv file directly from your browser, with no server round-trip.

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