JSON Flatten
Flatten JSON online free with dotted keys. Convert nested objects and arrays to dot notation in your browser. No upload, no account, no server processing.
Runs locally in your browser. Your input is not uploaded to DevToolMate servers.
Developer Quick Tips
- Paste JSON or upload a .json file; JSON flattener converts nested objects and arrays into dotted keys like users.0.name instantly in your browser.
- Array elements use numeric indexing in paths (roles.0, roles.1), perfect for preparing API payloads and normalizing logs before indexing.
- Flatten JSON online to inspect deeply nested config objects as a single-level key map without uploading to any server.
- Empty objects and arrays are preserved as leaf values; pair with JSON Unflatten to expand dotted keys back into nested structure.
- Free online JSON flattener runs entirely locally, your input never leaves your device, no account or signup required.
Frequently asked questions
What does flatten json online do?
Flatten JSON online converts nested JSON objects and arrays into a flat structure with dotted keys, all processed in your browser. For example, {user: {name: 'Alice'}} becomes user.name, and {users: [{name: 'Alice'}]} becomes users.0.name. No upload, no server processing, everything stays on your device.
How does a JSON flattener online handle arrays?
Array elements are indexed numerically in the dotted path. An array [item1, item2] at key 'roles' becomes roles.0 and roles.1. Nested arrays and objects within arrays are flattened recursively, so {users: [{name: 'Alice', tags: ['admin']}]} becomes users.0.name and users.0.tags.0.
What is dot notation in JSON?
Dot notation represents nested JSON paths as strings with dots separating keys. For example, a nested object {user: {name: 'Alice'}} becomes user.name. Arrays use numeric indices: {users: [{name: 'Alice'}]} becomes users.0.name. JSON Flatten converts your entire nested structure into this flat, dotted-key format.
How does JSON Flatten handle empty objects and arrays?
Empty objects {} and empty arrays [] are preserved as leaf values in the flattened output. This ensures you can distinguish between a missing key and an intentionally empty container when you unflatten later.
Does JSON flattener online upload my data?
No. JSON Flatten runs entirely in your browser. Your input is never uploaded to DevToolMate servers or any external service. Processing is completely local.
Can I unflatten JSON after flattening it?
Yes. Use JSON Unflatten to expand dotted keys back into nested structure. For example, user.name becomes {user: {name: 'value'}} again. Both tools work together for complete JSON transformation workflows.
Is the free JSON flattener online tool really free?
Yes. JSON Flatten is completely free with no account required. Processing stays on your device, and there are no hidden fees or limits.
Related tools
- JSON Unflatten: Flatten JSON online then unflatten back to nested objects and arrays. Free browser tool, no upload, no account. Rebuild nested JSON locally.
- JSONPath Query: Free jsonpath online tool to query JSON in your browser. Extract fields with dot notation, array indexes, and wildcards. No upload, no account, no server processing.