CSV to JSON Converter

CSV to JSON Converter is a free online tool for converting CSV (Comma-Separated Values) files to JSON format and converting JSON arrays back to CSV format. This bidirectional converter handles file uploads, parses CSV with proper header detection, converts data types automatically, and formats output beautifully—perfect for developers, data analysts, and anyone working with data transformation between CSV spreadsheets and JSON APIs. The tool processes everything client-side in your browser, ensuring complete data privacy with no server uploads. Common use cases include converting Excel/Google Sheets exports (CSV) to JSON for use in web applications and APIs, transforming API responses (JSON) to CSV for import into spreadsheet software, preparing data for JavaScript applications that consume JSON, creating CSV reports from JSON data returned by databases or APIs, converting legacy CSV data files to modern JSON format for web apps, formatting data for data visualization libraries that accept JSON, and transforming between formats when integrating different systems and tools. CSV (Comma-Separated Values) is a universal format supported by Excel, Google Sheets, and all database systems for exporting tabular data, while JSON (JavaScript Object Notation) is the standard format for web APIs, JavaScript applications, and modern data exchange. This tool bridges the gap between these formats seamlessly. The CSV to JSON conversion treats the first row as column headers and converts each subsequent row into a JSON object with keys from the headers, automatically detecting and converting number types (integers and floats) to proper JSON numbers rather than strings, handling quoted fields that contain commas or line breaks, and skipping empty lines. The output is formatted as a JSON array of objects with proper indentation for readability. The JSON to CSV conversion requires input as an array of objects with consistent keys, uses the object keys as CSV column headers in the first row, handles missing fields gracefully by inserting empty values, properly quotes fields containing commas or special characters, and produces standard CSV format compatible with Excel and Google Sheets. The tool includes convenient file upload for CSV files, a swap button to quickly reverse input and output (useful when chaining conversions), download functionality to save converted data directly to your device, real-time error detection with clear messages for invalid input, and syntax highlighting in the text areas for better readability. All data processing happens entirely in your browser using the battle-tested PapaParse library for robust CSV parsing and formatting. No data is ever sent to a server, and the tool works completely offline once loaded—your sensitive data never leaves your computer. This is essential for working with confidential business data, personal information, or any data with privacy requirements. The tool handles edge cases including CSV files with quoted fields containing commas or newlines, fields with special characters, inconsistent number of columns across rows, JSON objects with nested structures (flattening to CSV), missing properties in some JSON objects, and large files (tested with thousands of rows). Understanding CSV and JSON formats is essential for modern data work. CSV is universal for spreadsheet software but limited in structure (flat, no nesting), making it ideal for tabular data but not for hierarchical data. JSON is perfect for structured data with nesting, arrays, and different data types, and is the native format for JavaScript and web APIs, though it's not directly editable in Excel without conversion. Use this tool when migrating data between systems with different format requirements, transforming data exports from databases or analytics tools, preparing data for specific applications or APIs, converting spreadsheet data for use in web development, or batch processing data transformations. Works on all modern browsers including Chrome, Firefox, Safari, and Edge, on desktop, tablet, and mobile devices. The tool automatically handles character encoding (UTF-8) to support international characters and symbols. Perfect for quick one-time conversions or regular data transformation workflows, with no registration or installation required.