CSV to Nested JSON
Turn CSV with dot-notation headers back into nested JSON objects and arrays — with automatic type detection.
This tool runs 100% in your browser. Your data is never uploaded, stored, or logged.
Nested JSON
About this tool
This is the reverse of flattening: headers like user.name and tags.0 become real nested objects and arrays. The parser is fully quote-aware, auto-detects your delimiter, and can convert numbers, booleans and null into proper JSON types.
Perfect for promoting spreadsheet-maintained data into structured JSON your app can consume.
How to use it
- Paste CSV where the first row contains headers.
- Use dots for nesting (
address.city) and numbers for arrays (tags.0). - Leave delimiter on auto-detect, or set it manually.
- Copy or download the resulting JSON.
Useful ways to apply it
- Letting non-developers maintain data in a spreadsheet, then exporting to JSON.
- Rebuilding structured objects from a flattened CSV export.
- Converting lookup tables into JSON fixtures.
- Migrating CSV product feeds into API-ready payloads.
Frequently asked questions
How does type detection work?
Values like 42, 3.14, true, false and null convert to real JSON types. Everything else stays a string. You can turn this off to keep all values as strings.
Can it read semicolon or tab separated files?
Yes — auto-detect samples the first row, or you can pick the delimiter explicitly.
What about quoted values containing commas?
The parser is RFC-4180 aware: quoted cells, escaped double quotes and embedded newlines are all handled correctly.
Privacy
This tool runs 100% in your browser. Your data is never uploaded, stored, or logged.