CSV to JSON Converter: Local Files, Headers & Arrays

Convert CSV without changing cell values

All values stay strings. An account value of 00123 remains "00123", and an integer beyond JavaScript’s safe-number range retains every digit. Dates, booleans, and formula-looking cells are not inferred or evaluated.

Quoted fields and delimiters

Comma, semicolon, and tab separators are supported. Wrap a field in double quotes when it contains a delimiter or a line break. Represent a quote inside a quoted field using two quotes. Both CRLF and LF row endings are supported, along with a UTF-8 byte-order mark.

Objects or arrays?

Object output requires a first row with non-empty, unique headers. Surrounding header whitespace is trimmed. Duplicate or empty headers would lose information as object keys, so the tool reports an error. Array output preserves column order and supports headerless data; enable the header option to omit the first row from array data.

Limits and errors

Input supports 1 million decoded characters, 10,000 data rows, and 200 columns. Uploaded files must be UTF-8 and at most 2 MB. Rows must have a consistent column count. Malformed quotes are rejected rather than guessed. Large previews are truncated at 200,000 characters; downloads retain complete output up to 8 million characters.

Input contents, names, and converted JSON remain in this tab. No spreadsheet formulas are executed and no input is included in page analytics.

About this tool

Prepared by the UtilitiesWeb team at The Alpha 1 Company. Review results before using or sharing them.

Methodology updated: 1 November 2026. Inputs are processed locally; clearing or leaving the page releases the working result.