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CSV to JSON Converter

Paste text or open a file to convert CSV to JSON or JSON to CSV, with live output, a table preview, and a download button.

CSV to JSON Converter · saved on this device only

Use this CSV to JSON converter when you have a spreadsheet export, a log file, or a database dump and need it as JSON for an API, a script, or a config file. It also works the other way: paste an array of JSON objects and get a CSV that opens in Excel or Google Sheets. Semicolon, tab, and pipe-separated files are detected automatically.

The conversion runs in your browser, so your data stays on your device and nothing is uploaded to a server. The result updates as you type. Your input and settings are saved in your browser's local storage, so they are still there when you come back. “Clear” empties the input.

How to use it

  1. Pick a direction with the “CSV → JSON” or “JSON → CSV” tab at the top.
  2. Paste your data into the input box, or press “Open file” or drag a file onto the box. “Paste” reads from the clipboard, and “Example” loads sample data.
  3. Adjust the options bar. For CSV to JSON you can set “Delimiter”, “First row is header”, “Trim spaces”, “Detect numbers & booleans”, “Empty cells → null”, and “Format”.
  4. Check the result in the “JSON text” or “CSV text” tab, or switch to “Table preview” to see the rows and columns as a table.
  5. Press “Copy” to put the result on the clipboard, or “Download” to save it as a .json or .csv file.
  6. Press “Reverse” to send the result back in as input for the opposite conversion.

What it does

  • Delimiter auto-detection for comma, semicolon, tab, and pipe, with a “Delimiter” menu to set one yourself.
  • A “First row is header” switch: with it on you get an array of objects, with it off you get an array of arrays.
  • Optional cleanup for CSV to JSON: “Trim spaces”, “Detect numbers & booleans”, and “Empty cells → null”.
  • JSON output can be pretty-printed with 2 or 4 spaces, or minified.
  • JSON to CSV can flatten nested objects into columns like address.city. It also has an output delimiter menu, an “Include header row” switch, and a “Quote every field” switch.
  • A “Table preview” tab shows up to the first 200 rows, with row numbers and the header names.
  • Open or drop .csv, .tsv, .txt, .json, .jsonl, or .ndjson files. JSON files with one object per line are also accepted when pasted.
  • Warnings for problems such as an unclosed quoted field, and an error message when the JSON is invalid.

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Convert CSV to JSON and JSON to CSV with delimiter detection, header option, preview table, and download.

Questions

Is this CSV to JSON converter free?

Yes. It is free to use, with no account or signup needed.

Is my data uploaded anywhere?

No. The conversion runs in your browser and nothing is sent to a server. Your input and settings are saved in your browser's local storage on your device so they are restored next time, and “Clear” empties the input.

How do I save the converted file?

Press “Download” in the Result panel. It saves a .json or .csv file named after the file you opened, or “converted” if you pasted the text. “Copy” puts the result on the clipboard instead.

My CSV uses semicolons or tabs. Will it still convert?

Yes. With “Delimiter” set to “Auto-detect”, the tool tries comma, semicolon, tab, and pipe, and the status line under the input shows which one it picked. If it guesses wrong, choose the delimiter from the menu.

What happens to nested JSON when I convert it to CSV?

With “Flatten nested objects” on, nested objects become separate columns such as address.city. Arrays are written into the cell as JSON text.

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Updated October 12, 2026