CSV to JSON converter
Convert CSV to JSON or JSON to CSV locally. Handle quoted fields, choose comma, tab, or semicolon delimiters, and download your converted data.
Data stays in this tab; it is never written to the URL. CSV values remain strings, and headers are trimmed.
Parsing, conversion, preview, copying, and download generation run on your device. Neither input nor output is added to the page URL, uploaded, or stored in a history.
Only the tool and action can appear in consented analytics, never column names, cell values, filenames, input text, or error excerpts.
Use the clear button or leave the page to remove the working data from this tool. A copy you download or paste elsewhere remains on that destination.
Do not enter production secrets into any web page unless you are allowed to handle them there. This tool avoids uploads, but your browser, extensions, and device policies still matter.
Good for
Convert CSV records into an array of JSON objects.
Export flat JSON row objects with an explicit delimiter.
Inspect schema errors before importing a dataset.
Not for
This is not a spreadsheet engine or an Excel workbook reader.
CSV cannot preserve JSON types, missing versus null, or nested structures automatically.
Use quoted strings for large integer identifiers; JavaScript numbers are not arbitrary precision.
Additional Resources
Frequently Asked Questions
Does the converter upload my data?
No. Conversion happens in the browser tab. Local file reading and output downloads do not send your rows to Calculation Hub, and no data is written to URL parameters or a share link.
How are CSV headers and values interpreted?
The first non-empty line supplies the column names, trimmed of surrounding whitespace. Names must be unique and non-empty. Values remain strings, including leading zeros; blank physical lines are ignored and malformed row widths are rejected.
Can fields contain commas, quotes, or line breaks?
Yes. Enclose such fields in double quotes, and represent an embedded double quote with two double quotes. The parser accepts CRLF or LF row endings, a UTF-8 BOM, and comma, semicolon, or tab delimiters.
What happens to nested JSON and missing values?
Nested arrays or objects are rejected unless you select JSON text in cells. The export uses the union of property names across rows. Missing values and null become empty CSV cells, so conversion is not type-preserving.
How does spreadsheet formula protection work?
By default, formula-like string cells and headers beginning with equals, plus, minus, or at-sign after whitespace get an apostrophe prefix. This deliberately changes those strings. It reduces spreadsheet formula execution risk, but spreadsheet import behavior varies; inspect untrusted data before opening it.
What are the size and precision limits?
Input is limited to 1,000,000 characters, local files to 1 MiB, and tables to 10,000 data rows and 200 columns. Output is capped at about five million characters and previews at 20,000. Unsafe integer numbers are rejected; encode long numeric identifiers as JSON strings.