CSV/JSON Converter
Convert between CSV and JSON in either direction as you type, keeping every value exactly as written with no data-type guessing — free and entirely inside your browser.
🔒 Your code never leaves the browser — not one character is sent anywhere, and nothing is stored
How to use it
- Pick a directionCSV to JSON, or JSON to CSV.
- Paste your data into the first boxThe first line of a CSV file must be the column names (the header).
- Read the resultIt updates from the first character — and if something is wrong with the data, we say exactly where.
- Copy the resultCopy takes the whole second box.
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Frequently Asked Questions
Why does every value come out as a string, even numbers, after converting from CSV?
Because CSV has no data types to begin with — every cell is text, and guessing whether it means a number, a string or a date is a decision you never asked for. Guess wrong on a column like a phone number that starts with a zero ("0501234567") and the guess silently strips the leading zero and corrupts your data. So every value is kept exactly as written, and you convert it to the right type yourself when you actually need to.
What happens if a row has a different number of columns than the header?
We stop and tell you exactly which row, how many columns were expected, and how many we found — we don't pad the missing ones with blanks or drop the extra ones silently. Any automatic fix here means deciding which of your columns is wrong, and that decision has to be yours.
Do blank lines in a CSV file cause a problem?
No, they are skipped automatically — mid-file or at the end. The one exception: with a single-column CSV, a row holding a genuinely empty value looks identical to a blank line and gets skipped the same way rather than kept as an empty-value row. A narrow edge case, stated here plainly rather than hidden.
How is the column order decided when converting from JSON to CSV?
The header is every key seen across every object, in first-seen order. So if the first item has only "name" and "age" and a later item adds "city", the header comes out name,age,city — and the first row gets an empty cell under "city".
What happens to nested values (an object or array inside a field) when converting to CSV?
CSV has no way to represent nesting at all, so we write the value's own JSON text into the cell instead of dropping it or breaking it — better than silently losing your data. For a cleaner conversion, flatten your data before converting.
Does it support a delimiter other than a comma, like a semicolon?
Not currently — just the comma, following the standard RFC 4180 convention: double quotes around any field containing a comma, a newline or a quote, and a doubled quote to escape one inside the field.
Is my data uploaded to a server?
No, not one character. The whole conversion runs inside your browser, from the very first character you type.