Developer & Text · CSV ↔ JSON
Convert CSV to JSON and JSON to CSV on your computer
Quick answer
Paste or open data in Toolfox → CSV ↔ JSON and pick a direction. Quoted commas, line breaks in cells, Unicode and duplicate headers are handled, values stay text unless you ask for type detection, and nested JSON is flattened to “a.b” columns. It runs entirely on your computer (Mac, Windows or Linux). Files are never uploaded.
How to do it
- Open CSV ↔ JSON and paste data or open a file.
- Choose CSV → JSON or JSON → CSV and the delimiter.
- Decide on headers, type detection and nested-object handling.
- Copy or Save the result.
Options you can set
- Convert
- Delimiter
- First row is a header
- JSON shape
- Detect numbers & booleans
- Empty cells become null
- Require equal columns
- Pretty-print JSON
- Nested objects
Good to know
- JSON → CSV: arrays inside objects are written as JSON text; null becomes an empty cell.
- Quoted commas, escaped quotes, line breaks inside cells and Unicode are handled per RFC 4180.
CSV ↔ JSON FAQ
Will “007” become 7?
No. Leading zeros always stay text, and type detection is off by default.
How are nested objects written to CSV?
Flattened to dotted columns like address.city, or kept as JSON text, your choice. Arrays are written as JSON text.
Is CSV ↔ JSON in Toolfox free?
Yes. CSV ↔ JSON is one of 57 tools in Toolfox, a free app for Mac, Windows and Linux with no account, ads, limits or watermarks.
Does CSV ↔ JSON upload my files?
No. Toolfox processes files on your own computer and works offline; your files are never uploaded.
More developer & text tools in Toolfox
Get CSV ↔ JSON and 19 more tools.
Free forever. No account. Works offline. For macOS, Windows and Linux.
Updated 2026-10-18 · Toolfox v0.2.1