Automation & APIs · Free Tool
CSV to JSON Converter
Convert CSV to JSON or JSON back to CSV instantly, with header detection and array validation.
About this tool
This two-way converter turns CSV data into JSON arrays of objects, or flattens a JSON array back into CSV rows. Switch direction with the mode buttons, paste your data, and the conversion runs live as you type — the first row of a CSV is treated as the header, becoming the keys of each JSON object.
It is built for the glue work behind spreadsheets, exports, and APIs: turning a CSV dump from Google Sheets or Excel into JSON for a script or webhook, or flattening an API response into CSV for a stakeholder who just wants to open it in Excel.
Common uses
- Turn a CSV export from Excel or Google Sheets into JSON for an API call or script
- Convert a JSON array from an API response into CSV for a spreadsheet or report
- Validate that a CSV file is well-formed before feeding it into an import pipeline
Frequently asked questions
What happens to CSV rows with missing or extra columns?
The converter parses rows according to the header row and reports parsing warnings — such as inconsistent field counts — below the output so you can spot and fix malformed rows.
Does JSON → CSV work with nested objects?
No — the input must be a flat array of objects (no nested objects or arrays as values), since CSV has no native way to represent nested structures. Flatten nested fields first if you have them.
Which row becomes the CSV header?
For CSV → JSON, the first row is always treated as the header and becomes the object keys. For JSON → CSV, the header row is built from the keys of the first object in the array.
Is my data uploaded to a server?
No. This tool runs entirely in your browser using JavaScript — nothing you type is transmitted, logged, or stored anywhere. You can even use it offline once the page has loaded.