CSV to JSON & JSON to CSV
Switching between CSV and JSON formats is a common task for developers, data analysts, and anyone working with structured data. This free converter handles both directions at once: paste comma-separated values on the left to get a JSON array of objects on the right, or paste JSON on the right to produce a clean CSV table on the left. Edit either side directly and the other updates instantly. Everything runs in your browser; nothing you paste or upload is ever sent to a server.
When should I use CSV vs. JSON?
CSV (Comma-Separated Values) stores data in a flat, tabular format where each line is a row and commas separate fields — compact and widely supported by spreadsheets and databases. JSON (JavaScript Object Notation) uses key-value pairs and supports nested structures, making it the standard format for web APIs and configuration files. Choose CSV when you need simple, flat data that opens easily in Excel or Google Sheets, and JSON when you need hierarchical data or are working with web services. Once you have JSON output, you can clean it up further with the JSON Formatter.
Are numbers and booleans converted to their JSON types, or kept as text?
Kept as text. Every CSV cell becomes a JSON string, even a column that looks like numbers
or true/false values — an "age" column of 30 becomes the JSON string
"30", not the number 30. This matters if you're feeding the
output into code that expects real numeric or boolean types: you'll need to convert those
fields explicitly after importing the JSON, since this tool intentionally doesn't guess
at a cell's intended type.
Can I upload a CSV file instead of pasting it?
Yes — drag and drop a .csv file onto the drop zone above the editor, or click it to choose a file from your computer. The file is read entirely in your browser and its contents populate the CSV panel, which then converts to JSON exactly the same way as pasted text.
What happens if my JSON objects have different fields?
Converting JSON to CSV uses only the first object's keys as the column headers — it doesn't scan every object to build a combined list. If a later object has a field the first one doesn't, that field is silently dropped from the CSV; if the first object has a field a later one is missing, that row just gets an empty cell. If your data isn't uniform, make sure the first object in your JSON array includes every field you want as a column.
Last reviewed: August 2026