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CSV ↔ JSON Converter

Convert CSV to JSON and JSON to CSV with custom delimiters, clean downloads and private browser processing.

Private browser conversion

Convert structured data both ways

Handle CSV and JSON locally with reliable quotes, delimiters and nested values.

DelimiterFirst row is headerInfer typesEmpty as nullIndent

CSV inputDrop .csv or .json · max 20 MB

JSON output

Convert data to see row, column and size details.

Shortcut: Ctrl / Cmd + Enter to convert

How to convert CSV and JSON

Choose a direction

Select CSV to JSON or JSON to CSV at the top of the converter.

Add your data

Paste data, load a sample or drop a .csv or .json file into the editor.

Convert and export

Review the output, then copy it or download a clean JSON or CSV file.

Accurate CSV parsing

Quoted commas, line breaks and escaped double quotes are handled correctly. You can auto-detect common delimiters or choose comma, semicolon, tab or pipe manually.

Private by design

Conversion happens locally in your browser. Your CSV and JSON data is not uploaded to OptimizeFile.

CSV and JSON converter FAQ

Can the converter detect delimiters?

Yes. Auto detect checks comma, semicolon, tab and pipe-separated data. You can override it at any time.

Are quoted CSV fields supported?

Yes. Fields can contain delimiters, escaped double quotes and line breaks when wrapped in double quotes.

How are nested JSON objects handled?

Flatten nested keys creates columns such as profile.city. Turn it off to keep nested objects as JSON strings inside CSV cells.

Will type inference remove leading zeroes?

No. Values such as ZIP codes and phone-like numbers with leading zeroes remain strings.

What file size is supported?

You can open .csv and .json files up to 20 MB. Processing speed depends on your device and browser.