JSON Flattener

Flatten and unflatten nested JSON

Nested JSON is natural to write but awkward for some tools that want a flat key-value structure. This tool flattens a nested JSON object into single-level dot-notation keys, and unflattens it back, so you can move between the two shapes.

Why flattening helps

A deeply nested JSON object is expressive, but many tools, spreadsheets, some config systems, certain data pipelines, want flat keys. Flattening turns a nested structure into keys like user.address.city, one level deep, which those tools can handle, and the dot notation preserves the path so nothing is lost. Being able to unflatten reverses it, reconstructing the nesting from the dotted keys. Having both directions lets you convert data into whatever shape the next tool needs and back again, which is a common step when data crosses between systems that structure it differently.

Both shapes, one tool

It runs entirely in your browser, so nothing you paste is uploaded and the result is yours to copy straight into a project. Because it works client-side, you can use it on private code and data without anything leaving your machine.

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