Flatten JSON Files Online
Flatten nested JSON structures in JSON files into a flat table directly in your browser. Nested objects are expanded into prefixed columns — no upload required.
Drop your .json file here
or click to browse — max 50 MB
About this tool
Expand nested JSON objects inside a JSON file into flat columns. Nested keys become column names using dot notation, turning complex structures into a standard tabular format ready for analysis.
Frequently Asked Questions
What does flattening a JSON file do?
Nested JSON objects within the file are expanded into flat columns using dot notation. For example {"address": {"city": "Dublin"}} becomes a column named address.city.
How deeply does the JSON flattening go?
One level of nesting is expanded per run. For deeply nested structures you can flatten the output again, or use the SQL Query tool with json_extract for more control.
What happens to JSON arrays when flattening a JSON file?
Array columns are left as-is — only nested objects are expanded. To unnest arrays use the SQL Query tool with UNNEST().
Is my data private?
Yes — completely. Your file is never uploaded to any server. Everything runs locally in your browser using WebAssembly — processing happens entirely inside your tab. Once you close the tab, nothing is retained.
What is the maximum file size?
The free limit is 50 MB. For larger files, performance depends on your device's available memory — most modern machines handle 500 MB to 1 GB comfortably.
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