CSV to JSON Converter
Convert CSV or TSV to JSON locally. Preserve leading zeros, long identifiers and text values; catch malformed rows before copying or downloading.
Need to prepare CSV first? Edit columns and filter once, then export CSV, JSON or SQL.
1. Add your data
Processed only in this browser. No upload or storage.
Defaults: first row = column names; 00123, true, null and empty values stay text. Without headers, names are column1, column2, etc. Inference accepts only precision-preserving JSON numbers and true / false / null; leading zeros, unsafe numbers, empty or whitespace-padded cells stay text. No duplicate-header or missing-cell repairs.
Supported formats and limits
UTF-8; comma / semicolon / Tab / pipe; LF / CRLF; quoted separators, newlines and doubled quotes. Blank lines are not skipped. No Excel workbooks, Big5 or lone CR.
1 MiB input, 10,000 records, 200 columns, 200,000 data cells; 8 MiB output and a 5-second timeout. Spaces around header names are preserved.
Inference, headerless and JSON→CSV paths share a 100,000-cell limit including headers. JSON parsing allows 100 levels and 50,000 nodes; its root must be a nonempty array of objects. Auto counts separators outside quotes in the first logical record; ties require an explicit choice, and no separators defaults to comma. JSON export uses CRLF. Round trips do not restore original JSON types or nesting.
2. Get your JSON
Paste your data or load a sample, then convert.
Continue with JSON opens the full result in the workspace below. Each mode’s parsing limits still apply.
How to use this tool
Paste CSV or choose a UTF-8 file, select its separator, and convert. The first row supplies unique column names. Every value stays a string; copy or download the complete JSON array.
When not to use it
Not an Excel workbook reader or a data validator. No automatic type inference, header repair or missing-cell filling. Use your organization’s approved workflow for sensitive records.
Read the guide →