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CSV to JSON converter — UTF-8 and Shift_JIS

Convert CSV to JSON locally, including quoted commas and multiline cells. Read UTF-8 or Shift_JIS files and preserve leading zeros by default.

Convert in your browser · No sign-up

Up to 10 MB · Files are not uploaded

How to use

  1. Input CSV with a header row. Choose the encoding before importing a Shift_JIS file.
  2. Choose the delimiter and convert. Values remain strings by default.
  3. Review the first 100 records and download the complete JSON.

Example

CSV:
id,name
001,山田

JSON: [{"id":"001","name":"山田"}]

Details and limitations

Conversion data stays in this browser tab and is cleared on reload.

Limits: 10 MB input, 50,000 records, 2,000 columns and one million expanded JSON cells. Processing runs in a Web Worker.

Empty cells become empty strings. Duplicate headers or inconsistent widths are errors. Dotted headers remain literal keys.

Optional type inference converts numbers, true, false and null. Leading zeros such as 001 stay intact. Keep strings when exact decimal precision matters.