CSV ↔ JSON Converter
Convert CSV to JSON or JSON to CSV in one click. Handles quoted fields, custom delimiters, and nested objects. Nothing is uploaded.
CSV Input
JSON Output
What is this tool?
A two-way CSV and JSON converter that runs entirely in your browser. Paste CSV data and get structured JSON, or paste JSON and get clean, spreadsheet-ready CSV. Nothing is uploaded to any server.
Built for developers, analysts, and anyone moving data between systems — with proper handling of quoted fields, escaped characters, and nested structures.
What it handles
- Quoted fields with commas and newlines inside
- Custom delimiters: comma, semicolon, tab, pipe
- Type detection for numbers and booleans
- Nested objects flattened with configurable separator
- Arrays preserved as JSON strings in CSV cells
- Character encoding: UTF-8 in and out
FAQ
Is there a size limit?
No hard limit. CSV files up to a few megabytes convert fine. Anything beyond that depends on your device's memory — since nothing is uploaded, the bottleneck is your browser, not a server.
Why does my CSV look wrong after converting?
The most common cause is the wrong delimiter. If your file uses semicolons (common in European locales where comma is the decimal separator), select "Semicolon" in the delimiter dropdown.
What does "Flatten nested objects" do?
When converting JSON to CSV, a nested object like {"user":{"name":"Ada"}} becomes a flat column called user.name with the value "Ada". You can change the separator.
Can I convert CSV with headers that don't match?
Yes. If "First row is header" is off, columns are named col1, col2, etc. If it's on, the first row's values become the JSON keys.
Is this safe for sensitive data?
Yes — nothing leaves your device. Open DevTools' Network tab while converting and you'll see zero outbound requests. This is verifiable, not a marketing claim.