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.
Where you'd use this
The join between spreadsheets and code. Finance exports CSV, your API speaks JSON, and someone has to translate — usually with commas inside quoted fields waiting to ruin a naive split.
For example: A 5,000-row export of orders needs loading into a test database. Converting to JSON handles the quoted "Smith, John" name fields correctly, where a spreadsheet re-save had already split them into two columns.
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.