Flatten Nested JSON Online
Convert deeply nested JSON objects into a flat, single-level structure using dot-notation keys. This makes nested data ready for CSV export, database insertion, or tabular analysis. All processing runs client-side in your browser.
JSON to CSV Converter
Convert JSON arrays to CSV format. Automatically flattens nested objects with dot notation, lets you select columns, and download as a .csv file.
About JSON to CSV Conversion
- Nested objects are flattened using dot notation (e.g.
address.city). - Arrays within objects are serialized as JSON strings in the CSV output.
- Select or deselect columns after converting to customize your output.
- Supports comma, tab, semicolon, and pipe delimiters.
- Download the result as a .csv file ready for Excel, Google Sheets, or any spreadsheet app.
- Everything runs in your browser — no data is sent over the network.
What does it mean to flatten JSON?
Flattening JSON transforms a hierarchical object with nested children into a single-level object where each key uses dot notation to represent its path. For example, {"user": {"name": "Alice"}} becomes {"user.name": "Alice"}. This is essential when you need to represent complex JSON as rows in a spreadsheet or relational database table.
Common use cases
JSON flattening is commonly needed when exporting API responses to CSV or Excel, preparing data for flat-file databases, building search indexes from nested documents, and creating reporting dashboards that require tabular data. It is also useful for comparing two nested objects by reducing them to flat key-value pairs.
Frequently Asked Questions
How are nested arrays handled when flattening JSON?
Array elements are flattened using numeric index notation, such as items.0.name and items.1.name. This preserves the order and structure of the original array within the flat key-value output.
Can I unflatten the JSON back to its original structure?
Yes, flattening is reversible. The dot-notation keys contain enough path information to reconstruct the original nested structure. Many JSON utility libraries include an unflatten function for this purpose.