CSV ↔ JSON Converter
Convert CSV or TSV to JSON and back — with real RFC 4180 parsing (quoted fields, embedded commas and newlines), delimiter auto-detection, header and type options, and file open/download. Your data never leaves your browser.
New to this? Read the CSV ↔ JSON Converter guide →
What the converter handles
- Real CSV, per RFC 4180: quoted fields, embedded commas, doubled quotes ("") and line breaks inside quotes all parse correctly — the cases naive split-on-comma code gets wrong.
- Delimiter auto-detection for comma, semicolon (common in European exports), tab (TSV) and pipe, plus a manual override.
- Headers and types: use the first row as JSON keys, and optionally detect numbers and booleans so "42" becomes 42. Leading-zero values like postcodes stay strings.
- JSON → CSV: arrays of objects become a spreadsheet with a union of all keys as columns (missing values left blank); nested objects are embedded as JSON strings.
- Files: open a .csv straight from disk and download the result. Everything runs in your browser — spreadsheets full of names and salaries never leave your machine.
Working with JSON Lines (one object per line, common in ML datasets and log exports)? Use the JSONL converter — CSV → JSON here, then JSON → JSONL there. And the guide explains why CSV is trickier than it looks.
Frequently asked questions
Does it handle commas and line breaks inside CSV values?
Yes — parsing follows RFC 4180, so quoted fields, embedded commas, doubled quotes ("") and line breaks inside quotes all convert correctly. Those are exactly the cases that break naive split-on-comma code.
Can it convert semicolon-separated or tab-separated files?
Yes. The delimiter is auto-detected (comma, semicolon, tab, pipe) with a manual override — semicolon CSVs are standard from Excel in locales that use a decimal comma, and tab covers TSV.
How does JSON → CSV handle objects with different keys?
Columns are the union of every object’s keys, with blanks where a row lacks a value. Nested objects and arrays are embedded as JSON strings so the conversion round-trips.
Is my spreadsheet data uploaded?
No. Parsing, conversion, file opening and download all run locally in your browser — a spreadsheet of names and salaries never leaves your machine.