JSON to CSV Converter
Transform JSON records into structured CSV spreadsheets with nested flattening, custom delimiters, and live table preview.
- Runs in your browser
- Free, no signup
id,name,email,role,active,salary,location.city,location.country,skills 101,Sarah Connor,sarah@example.com,Lead Architect,true,125000,Austin,USA,PHP; JavaScript; SQL 102,Alex Murphy,alex@example.com,Security Specialist,true,115000,Detroit,USA,Cybersecurity; Python 103,Ellen Ripley,ripley@example.com,Flight Officer,false,130000,Seattle,USA,Operations; Robotics
Conversion runs entirely in your browser using local JavaScript — your JSON files and data records are never uploaded to any server.
Transforming JSON data into CSV (Comma-Separated Values) format is a daily task when exporting API responses, database dumps, and analytics records into spreadsheet applications like Microsoft Excel, Google Sheets, or Apple Numbers. This tool provides an instant, private, and flexible converter that works directly inside your browser.
Designed for software developers, data analysts, and QA engineers, the converter intelligently handles top-level arrays, single objects, and nested payloads. Choose between standard comma delimiters, semicolons for European Excel compatibility, tabs for TSV files, or custom pipes. Inspect your data visually in the built-in Table Preview before downloading.
How to use this tool
- Paste your JSON array or object into the input editor, or click "Load Sample" to explore realistic data.
- Configure options: choose your delimiter (Comma, Semicolon, Tab, or Pipe) and toggle nested object flattening.
- The tool immediately parses your JSON, generates compliant CSV, and renders a live table preview.
- Click "Copy CSV" to copy to your clipboard, or click "Download CSV" to save a ready-to-open spreadsheet file.
Intelligent Nested Object Flattening
JSON structures often contain nested objects (such as {"user": {"profile": {"age": 30}}}). When flattening is enabled, nested keys are cleanly collapsed into dotted column headers (e.g., user.profile.age), ensuring zero data loss and preserving clean spreadsheet columns.
Arrays of primitive values (e.g., tags or roles) can be kept as inline JSON strings or joined with separators, allowing downstream tools like pandas or Excel to process multi-value fields easily.
Strict RFC 4180 CSV Quoting and Escaping
Broken CSV files frequently occur when values contain commas, line breaks, or quotation marks. ToolDuck implements strict RFC 4180 escaping: fields with special characters are automatically wrapped in double quotes, and embedded quotes are safely doubled ("").
This guarantees that whether you open the resulting file in Excel, Google Sheets, LibreOffice, or import it into a PostgreSQL / MySQL database, the columns will never shift or break.
Support for Semicolon (European Excel), TSV, and Custom Delimiters
Depending on regional settings, Excel in many countries expects semicolons (;) rather than commas, because the comma is used as a decimal separator. ToolDuck allows you to select Comma (,), Semicolon (;), Tab (TSV), or Pipe (|) with a single click.
Selecting Tab instantly configures the exporter for Tab-Separated Values (.tsv), which pastes seamlessly into existing spreadsheets without prompting import dialogs.
100% In-Browser Privacy Guarantee
Customer lists, financial reports, and database records should never be uploaded to third-party conversion servers. ToolDuck executes all parsing and CSV construction locally in your web browser.
No files are uploaded to our servers, no third-party analytics see your rows, and your data remains strictly private on your device.
Frequently asked questions
What JSON structure does the converter require?
The most common structure is an array of objects (e.g. [{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}]). However, the converter also accepts a single object (which outputs a 1-row CSV) or an API response wrapper object containing a list property (like {"items": [...]}).
How does the converter handle nested objects and arrays?
By default, nested objects are flattened into dotted column names (e.g., address.city, address.zip). If you disable flattening, the nested object is preserved as a raw JSON string within a single cell.
Can I generate a file for European Excel that uses semicolons?
Yes. Simply select Semicolon (;) from the Delimiter dropdown. Excel in regions where the comma is a decimal separator will open the file cleanly without merging columns.
What is the file size limit?
Because conversion runs in your browser, it can process tens of thousands of rows smoothly depending on your device memory. Conversion is debounced and streaming buffers ensure UI responsiveness.
Are my JSON files uploaded or stored on any server?
Never. All processing occurs 100% client-side in your browser. No files, records, or personal data are ever transmitted to our servers.