Convert CSV and JSON while keeping your data understandable

Understand the settings

CSV is a text format with a delimiter between fields. A comma inside a field is not a separator when the field is quoted. A literal quote inside a quoted field is written twice. Quoted fields can also contain line breaks, so splitting a file on every comma or newline is not a reliable CSV parser.

CSV-to-JSON treats the first row as column names and requires those names to be non-empty and unique. Every later row must have the same number of fields. Values stay strings: 00123 remains 00123, and a long identifier is not rounded into a JavaScript number. JSON-to-CSV accepts an array of objects and uses the union of their keys as columns.

A spreadsheet may treat a cell starting with =, +, -, @, a tab or a carriage return as a formula. Export protection prefixes such cells with an apostrophe. That changes the exported text deliberately; switch it off only when you understand how the destination will interpret the values. It is not a universal guarantee against every spreadsheet import behavior.

Step by step

1. Paste text or load a UTF-8 file. Choose comma, semicolon or tab as the delimiter.
2. Select CSV-to-JSON, JSON-to-CSV or duplicate-row removal.
3. Use Load example to see a quoted comma and a quoted multiline field.
4. Process and inspect the result before copying or downloading. For deduplication, the header is retained and later identical rows are removed.

Keep an identifier as text

CSV with header code,name and row 00123,Avery becomes an object whose code is the string "00123". This avoids losing the leading zeros. In JSON-to-CSV, a nested object or array becomes JSON text inside a single cell.

Limits and what to check

• Input limit: 1,000,000 characters and 10,000 rows. Files are decoded as UTF-8.
• Whitespace and letter case are significant for duplicate matching. The first copy remains in its original position.
• CSV does not carry rich cell types, formulas, workbook sheets or formatting. This is not an XLSX editor.
• All parsing happens in the browser. Nothing is uploaded by this tool.

Troubleshooting