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JSON Unflatten

A JSON unflatten tool rebuilds nested structures from flat key paths. If you have data where keys look like user.address.city or items.0.name, this tool can turn those flat entries back into properly nested objects and arrays.

Why this matters

Flattened JSON is often convenient for export and storage, but not always ideal for application logic or configuration files. When you need the original hierarchy back, unflattening saves you from rebuilding the object structure manually.

What you can control

The tool lets you choose the separator character and optionally reconstruct arrays from numeric keys. That makes it flexible enough for different flattening conventions used by APIs, data pipelines, and custom scripts.

Because everything happens locally in the browser, you can safely restore nested JSON from flat data without uploading internal structures anywhere.