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JSON Unflatten

Free online JSON unflatten tool. Convert flat dot-notation keys back into nested JSON objects. Reverse of flatten. Runs locally in your browser, no data uploaded. 100% Local

How to Use the JSON Unflatten

Paste a flat JSON object with dot-notation keys into the input box. Click Unflatten and the keys are parsed back into nested objects and arrays. Use Clear to reset both panels.

How paths are interpreted

• Dot-separated segments create nested objects: user.name
• Bracket segments with numbers create arrays: items[0].id
• Mixed notation is supported: user.address.city
• Top-level keys without dots remain as-is

Features

• Automatically detects whether a path should create an array or object
• Handles deeply nested flat keys without limit
• Reversible with the Flatten tool
• All processing runs locally in your browser. Your data is not uploaded to any server.

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