Two very different shapes for the same data
CSV and JSON solve similar problems in genuinely different ways — one's a flat spreadsheet, the other's a nested, flexible structure. Moving data between them is a routine need for anyone working with exported data or an API. This tool converts both directions directly in your browser, with nothing ever uploaded.
Using it
- Paste or upload your CSV or JSON data.
- Convert to the other format.
- Copy or download the result.
Common uses
- Converting an exported spreadsheet into JSON for use in code.
- Turning an API's JSON response into a CSV for a spreadsheet.
- Reformatting data between two systems that expect different formats.
Advantages and limitations
Advantages
- Instant, no size limit tied to an upload
- Handles flat, tabular data cleanly in both directions
Limitations
- Deeply nested JSON doesn't convert cleanly to CSV
- Doesn't infer data types — everything converts as text by default
Where the two formats genuinely don't match
CSV is fundamentally flat — rows and columns, nothing more. JSON can represent real structure: an object nested inside another object, or an array of multiple values sitting within a single record. That kind of nested data simply doesn't have a clean equivalent in a flat spreadsheet. Converting deeply nested JSON to CSV usually means the structure has to be flattened or simplified somehow — this is an inherent limitation of what CSV can represent, not something any converter can fully solve. Simple, flat JSON (a list of records with plain key-value pairs) converts cleanly in both directions.
Pairs well with
Need to check the JSON output is well-formed? The site's JSON Formatter & Validator catches syntax issues instantly.
Frequently asked questions
+Is this converter really free, with no sign up?
Yes. There's no account and no limit on how much data you can convert.
+Is my data sent anywhere?
No. Conversion happens directly in your browser — nothing you paste or upload is ever transmitted.
+Why does converting JSON with nested objects to CSV look strange?
CSV is fundamentally a flat, two-dimensional format — rows and columns, nothing more. JSON can represent nested structures (an object inside another object, or an array of values within a single record) that simply don't map cleanly onto a flat spreadsheet. Deeply nested JSON often needs to be flattened or restructured before it converts to CSV in a genuinely usable way — this is a structural limitation of CSV itself, not something a converter can fully work around.
+Does the first row need to be a header?
Yes, for CSV-to-JSON conversion — the first row's values become the key names for every JSON object generated from the rows beneath it.