CSV to JSON Converter — Free & In Your Browser
Spreadsheet data in, clean JSON array out — types detected, quoting handled.
🔒 Runs in your browser — files never uploaded ⚡ No signup 💯 Free
Paste CSV — exported from Excel, Sheets or a database — and get a clean JSON array of objects, keyed by the header row. The delimiter is auto-detected (comma, semicolon or tab, covering the European semicolon convention), quoted fields with embedded commas and line breaks parse correctly, and numeric and boolean values become real numbers and booleans rather than strings.
Everything runs in your browser — business data stays on your machine.
How to use CSV to JSON
- Paste your CSV. Copying cells straight out of Excel or Sheets works — that arrives tab-separated and is detected automatically.
- Check the options if needed: untick the header row if your file has none, or force a delimiter.
- Copy or download the JSON from the right-hand pane.
What the header row becomes
With the header option on (the default), each data row becomes an object keyed by the header: name,born over Ada,1815 gives {"name":"Ada","born":1815}. Without it, rows become plain arrays. Empty header cells get generated names (column3) so no data is dropped.
Type detection, and its limits
1815 becomes the number 1815, true/false become booleans, null becomes null. Everything else stays a string — including things like 007 and 1e that only look numeric, which is exactly when auto-typing corrupts data (leading zeros in phone numbers and postcodes are the classic casualty). If a column must stay text, quote it in the source.
Semicolons and tabs
Excel in most of Europe exports CSV with semicolons (because the comma is the decimal separator), and copy-pasting cells produces tabs. Auto-detection handles both by counting candidates in the first row; the dropdown overrides it for pathological files.
Related
Mirror direction: JSON to CSV. For eyeballing the result, the JSON formatter pretty-prints and validates.
Frequently asked questions
My CSV uses semicolons — will it work?
Yes. The delimiter is auto-detected from the first row (commas, semicolons and tabs are all candidates), which covers the European Excel convention. If detection guesses wrong on an unusual file, force the delimiter from the dropdown.
Why did "007" stay a string but "1815" became a number?
Deliberately. Only values that survive a strict numeric round-trip are converted — 007 would come back as 7, silently corrupting codes, phone numbers and postcodes. That's the most common CSV-to-JSON data-loss bug, and this converter refuses to have it.
Can I paste straight from Excel or Google Sheets?
Yes — copied cells arrive tab-separated, which the auto-detection recognises. Select a range, copy, paste here, done.
What if my file has no header row?
Untick "First CSV row is headers" and rows become plain arrays instead of keyed objects — no invented column names, no first record eaten as a header.
How do quoted fields with commas and line breaks behave?
They parse correctly per RFC 4180 — a quoted field can contain commas, escaped quotes ("") and even line breaks. Naive split-on-comma converters break on all three; this one is a real parser.