CSV ⇄ JSON CONVERTER
Convert CSV to JSON or JSON to CSV with auto-detect delimiters
Everything runs locally in your browser. Your data never leaves your device - no uploads, no servers, no server processing.
All processing happens directly on your machine using JavaScript. Close the tab and all conversion data is gone.
Conversion analytics
Choose mode
Choose CSV to JSON or JSON to CSV conversion
Input data
Upload file or paste your data directly
Export result
Download converted file instantly
Why choose this CSV converter?
2-mode converter with auto-detect delimiters and nested JSON handling
Bidirectional conversion
Convert CSV to JSON or JSON to CSV with one click. One tool for all your data transformation needs.
Auto-detect delimiter
Automatically detects CSV delimiter (comma, semicolon, tab, pipe). Analyzes first rows for accurate detection with TSV file support.
Nested data handling
Choose how to handle nested JSON: flatten to dot notation (address.street) or stringify objects. Arrays convert to JSON strings.
Advanced options
Configure delimiters, headers, formatting, and output structure to match your exact needs.
File support
Drag & drop CSV, JSON, TXT, and TSV files for instant conversion and analysis.
Swap functionality
Instantly reverse input/output and switch conversion direction. Transform CSV to JSON result back to CSV with one click.
Frequently Asked Questions
CSV to JSON and JSON to CSV conversion FAQ
How to convert CSV to JSON?
Choose CSV to JSON or JSON to CSV mode, upload your file or paste data, configure options like delimiter and headers, then click Convert. The tool automatically generates your desired output format instantly.
What file formats are supported?
You can upload CSV, JSON, TXT, and TSV files. The tool supports all standard delimiters and automatically detects format settings.
How does JSON to CSV work?
Switch to JSON to CSV mode, input your JSON data, choose delimiter and header options, then convert. The tool flattens nested objects automatically.
Can I handle large files?
Yes, the converter handles large files efficiently. Processing happens locally in your browser with no file size limit beyond available memory.
Are there export options?
Yes, you can download converted files, copy to clipboard, or view real-time statistics during conversion.
Is my data secure?
All processing happens locally in your browser. No data is uploaded to servers or stored anywhere. Your CSV and JSON data stays in volatile memory and is erased when you close the tab.
Technical Details
How this CSV to JSON converter parses and transforms data
Custom CSV Parser
This CSV to JSON converter online uses a custom JavaScript parser that handles quoted fields, embedded commas, newlines within fields, and escaped double quotes per RFC 4180. Auto-detects delimiters by sampling the first 5 lines and scoring comma, semicolon, tab, and pipe frequency. First row is always treated as headers.
Zero-Upload Architecture
All CSV and JSON processing runs in your browser using client-side JavaScript. No data is uploaded to any server - no API calls, no cloud processing, no third-party access. Your data stays in volatile browser memory and is erased when you close the tab.
Bidirectional Conversion
Convert CSV to JSON as an array of objects with pretty-printed or minified output. Reverse direction converts JSON back to CSV with proper field escaping. Nested JSON objects are flattened to dot notation (address.street) or stringified. Supports 4 delimiter types and TSV files.
Performance
Real-time preview updates as you edit with 500ms debounced auto-conversion. Download output as .json or .csv file directly from your browser. Copy to clipboard with one click. Auto-convert is forced on mobile for instant feedback.
Nested Data Handling
When converting JSON to CSV, nested objects support two modes: flatten converts nested keys to dot notation (e.g., address.city becomes a column header), while stringify preserves nested objects as JSON strings in CSV cells. Arrays are always converted to JSON strings regardless of mode.
Conversion Analytics
Built-in analytics track total conversions, characters processed, copy and download counts, and per-mode usage statistics. The productivity score algorithm evaluates conversion volume, copy ratio, and dual-mode usage. All statistics persist across sessions using IndexedDB with zero server dependency.