CSV ↔ JSON Converter (Free)
Convert CSV to JSON or JSON to CSV in your browser. Choose comma, tab, or semicolon, toggle the header row, and copy or download the result. The parser handles quoted fields, doubled quotes, and line breaks inside quotes. Files stay on your device; there is no signup, upload, or tracker.
Hand-rolled parser for simple quoted CSV. It supports doubled quotes and quoted newlines, but not comments or exotic dialects.
How to convert CSV and JSON without sending data anywhere
Paste CSV or JSON into the input box, pick the delimiter, and choose a direction. CSV → JSON turns the first row into object keys when the header box is checked, or keeps every row as an array when it is not. JSON → CSV requires a top-level array. An array of objects produces a header row plus one row per object, and an array of arrays is written row by row. Cell values that contain the delimiter, a double quote, or a line break are wrapped in quotes and their internal quotes are doubled.
The parser is deliberately small. It understands quoted fields, doubled quotes, and line breaks inside quotes, which covers most exports from spreadsheets, databases, and CRMs. It does not understand comments, backslash escapes, a custom quote character, or every regional dialect. A quote that appears in the middle of an unquoted field is treated as a literal character rather than as the start of a quoted field. If your file uses an unusual dialect, test a few rows first and compare the output with the original.
CSV has no types, so CSV → JSON exports every cell as a string, including numbers and booleans. Convert those values in your application when you need real types. On the JSON → CSV side, keys are collected in the order they first appear across the objects, and missing keys become empty cells. Duplicate header names collapse because object keys must be unique, and extra CSV cells beyond the header are ignored. Nested objects and arrays are serialized as JSON text inside a single cell.
Both directions run locally. There is no coded size limit, but conversion happens on the main thread, so multi-megabyte files can make the tab slow. The tool also strips a leading UTF-8 byte order mark that some spreadsheet programs add. Download writes converted.json or converted.csv depending on the last conversion. No data is sent to superniche.im.
FAQ
Is this CSV to JSON converter free?
Yes. It runs in your browser with no signup, no payment, and no upload. There is no usage limit and no account is required.
Which CSV features are supported?
The parser supports comma, tab, and semicolon delimiters, quoted fields, doubled quotes inside quoted fields, and line breaks inside quotes. It does not support comments, a custom escape character, or every vendor-specific dialect.
Why are my JSON values strings after converting from CSV?
CSV does not carry type information, so every cell is exported as a string. Convert numbers and booleans yourself after import if your application needs real JSON types.
What shape of JSON can I convert to CSV?
The top level must be an array. An array of objects becomes a header row plus one row per object, and an array of arrays is written row by row. Nested objects are serialized as JSON text inside their cell.
Does the header row toggle matter in both directions?
Yes. In CSV to JSON it decides whether the first row becomes object keys or stays as data. In JSON to CSV it decides whether an array of objects gets a header row.
How large can my file be?
There is no coded byte limit, but conversion runs on the main thread and very large files can freeze the tab. For files beyond a few megabytes, use a command-line tool or a desktop spreadsheet program.