JSON Flattener
Flatten deeply nested JSON objects and arrays into simple dot-notation key-value pairs instantly. Free, no signup, works in your browser.
Everything runs inside your browser — your file is never uploaded to a server.
About this tool
Paste or upload a nested JSON document and this tool collapses every nested object and array into flat, dot-notation keys like address.city or items.0.price, producing a single-level structure that's far easier to read, search or convert into a spreadsheet. It's especially useful before exporting JSON to CSV or Excel, since flat keys map directly to columns without losing information buried several levels deep. The flattener preserves data types, correctly indexes array elements, and lets you copy or download the result as a new flat JSON file. Because everything runs locally in your browser using JavaScript, API payloads, configuration files or exported records with sensitive fields never get uploaded anywhere. This makes debugging deeply nested API responses or preparing data for analysis noticeably faster.
How to use this tool
1. Add your JSON
Paste JSON text or choose a .json file from your device.
2. Preview the flattened keys
Check the dot-notation keys generated from your nested structure.
3. Flatten
Click flatten to collapse nested objects and arrays into flat keys.
4. Copy or download
Copy the flattened JSON or download it as a new .json file.
Why use this tool
Deeply nested JSON is hard to scan, search or convert into a spreadsheet without losing context. This tool flattens any structure instantly into predictable dot-notation keys, making it much easier to debug API responses, prepare data for CSV export, or compare records side by side.
Tips & best practices
- Use flattened output as a preparation step before converting JSON to CSV or Excel for cleaner columns.
- Watch for very deep nesting producing long key names; consider renaming columns after export if needed.
- Flatten one representative object first to check the key structure before processing a large array.
Common use cases
- Debugging a deeply nested API response by viewing it as flat key-value pairs.
- Preparing nested JSON data for a clean CSV or Excel export.
- Comparing two similar JSON records side by side after flattening both.
- Simplifying configuration files for easier searching and editing.
- Flattening exported analytics or event data for import into a spreadsheet tool.
Frequently asked questions
How are nested arrays represented after flattening?
Array elements become indexed keys, like items.0.name and items.1.name, so every value keeps a unique, traceable path.
Does flattening lose any data from deeply nested objects?
No, every value is preserved; only the structure changes from nested objects into flat dot-notation keys.
Can I flatten a JSON array of many objects at once?
Yes, each object in the array is flattened independently, keeping their structure consistent for comparison or export.
Is flattened JSON useful before converting to CSV?
Yes, flat keys map directly to spreadsheet columns, which is why flattening first often produces cleaner CSV or Excel exports.
Is my JSON data uploaded to a server during flattening?
No, the entire process happens in your browser and your data never leaves your device.
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