Is my CSV uploaded?
No. Parsing happens in the browser tab. After the page loads it makes no network requests.
Convert CSV to JSON
Drop a CSV, get clean JSON. Headers become keys, type inference included. Nothing uploaded.
Drop files here or
What actually goes wrong when people convert CSV
CSV looks simple until it is not. A field containing a comma needs quotes, a field containing a quote needs doubled quotes, a file saved by Excel on Windows starts with a byte-order mark that silently corrupts your first column name, and line endings may be CRLF. Naive splitters fail on all four, and they fail quietly: you get JSON that parses fine and is wrong.
This converter parses according to RFC 4180, strips the BOM, normalises CRLF, and infers numbers and booleans so the JSON is usable without a second pass.
Conversion behaviour
The details that decide whether the output is usable downstream.
| Conversion behaviour | Behaviour | Notes |
|---|---|---|
| Delimiter | Comma, auto-detected alternatives | Semicolon and tab are detected automatically, which matters for European Excel exports. |
| Quoting | RFC 4180 | Commas, quotes, and newlines inside quoted fields are preserved correctly. |
| BOM | Stripped | Excel's UTF-8 BOM otherwise becomes part of your first key and breaks every lookup. |
| Line endings | CRLF and LF both accepted | Windows exports do not leave a trailing carriage return in the last column. |
| Type inference | Numbers and booleans | 123 becomes a number, true becomes a boolean. Header-only columns stay strings. |
| Output | Array of objects | One object per row, keyed by header. Empty cells become empty strings, not null. |
Common mistakes
Editing CSV in Excel before converting
Excel re-quotes only what it thinks needs quoting and will happily mangle long numbers into scientific notation. Convert the original file.
Assuming your header has no spaces
A header like `First Name` becomes a key with a space. JSON allows it but most code does not want it. Rename headers in the CSV first.
Duplicated column names
Two columns called `id` produce one key: the second silently overwrites the first. Check the header row.
Expecting nested structure
Flat CSV converts to flat JSON. Anything hierarchical has to be reshaped after conversion.
Ignoring encoding
A CSV saved as Latin-1 with accented characters produces mojibake. Re-export as UTF-8 first.
Questions
How large a file can it handle?
Comfortably into the tens of megabytes. The limit is your browser's memory, not this tool.
Does it handle semicolon CSV?
Yes, the delimiter is detected automatically, so European Excel exports work without changing settings.
What about commas inside quoted fields?
They are preserved. The parser follows RFC 4180 rather than splitting on every comma.
Does it convert numbers to actual numbers?
Yes, numeric-looking values become JSON numbers rather than strings. Turn this off if you need IDs kept as strings.
Can it convert JSON back to CSV?
Yes, there is a separate JSON to CSV tool on this site.
Will my Excel BOM break the first column?
No, the byte-order mark is stripped before parsing.
Can I get the output as a file?
Yes, download the JSON directly from the results panel.
Need this without a browser tab?
FileKit Desktop runs every conversion locally as a single offline file — no 10-file limit, batch conversion, and no network connection required. One-time $19, no subscription.
See FileKit Desktop — $19