Usage Guide
How to use CSV to JSON conversion?
Paste CSV data in the left input box, select the correct delimiter (default is comma), and the tool will automatically convert CSV to a JSON array. You can check "First row is header" to auto-detect column names, check "Parse nested keys" to generate nested objects (using dot notation like user.name), and check "Parse arrays" to convert comma-separated values into arrays (using tags[] syntax). The conversion result appears in real-time in the right output box.
How to use JSON to CSV conversion?
Switch to "JSON → CSV" mode and paste JSON array data. The tool will automatically extract all fields as CSV column names. Nested objects are flattened into dot-notation column names (like user.name). You can customize the output delimiter and choose whether to include the header row. The converted CSV can be copied to clipboard or downloaded as a file.
Frequently Asked Questions
Does this tool upload my data?
Absolutely not. All conversions happen entirely in your browser using pure JavaScript — no data is sent to any server. You can verify this by opening the browser's developer tools (F12) and checking the Network tab. This page can even be downloaded and used offline.
What's the difference between CSV and JSON? When should I use which?
CSV (Comma-Separated Values) is a tabular format suitable for spreadsheet software like Excel — compact file size, easy to view and edit. JSON (JavaScript Object Notation) is a structured format that supports nested objects and arrays, ideal for API data exchange and programmatic processing. Use CSV for data storage and display, JSON for data transmission and consumption.
Which delimiters are supported? Can it handle fields containing commas?
Comma, semicolon, tab, pipe, and custom delimiters are supported. For fields that contain the delimiter character, the tool correctly handles double-quoted fields per RFC 4180. For example, "hello, world" will be recognized as a single field rather than split by the comma.
Can it generate nested JSON objects?
Yes. When the "Parse nested keys" option is enabled, dot-notation headers generate nested objects. For example, headers user.name and user.age produce {"user": {"name": "...", "age": "..."}}. When "Parse arrays" is enabled, the tags[] syntax converts comma-separated values into arrays.
How are nested objects handled when converting JSON to CSV?
When converting JSON to CSV, nested objects are flattened into dot-notation column names. For example, {"user":{"name":"John"}} produces the column name user.name. Array type fields are joined with commas by default. The tool automatically extracts all possible fields as columns to ensure data completeness.
How can I use the converted results?
Results can be copied to clipboard with one click or downloaded as a file (CSV to JSON downloads as .json, JSON to CSV downloads as .csv). You can adjust JSON output format (2-space / 4-space indent or minified), and CSV output can customize delimiters and include/exclude headers.