BYTETOOLS

JSON Flattener

Flatten nested JSON into single-level dot-notation keys online. Choose the separator, bracket or dotted array indexes, and copy or download the result.

Drop a .json file here or click to browse

What is the JSON Flattener?

The ByteTools JSON Flattener turns a deeply nested JSON document into a single-level object whose keys are full paths, such as user.

  • Recursive flattening of nested objects and arrays
  • Dot, underscore, slash or hyphen separators
  • Bracket items[0] or dotted items.0 array indexes
  • Optionally keep empty objects and arrays as values
  • Flat JSON or plain key = value output
  • 100% private — JSON never leaves your browser

How to use the JSON Flattener

  1. 1

    Paste your nested JSON into the input box, or drop a .json file to load it.

  2. 2

    Choose the key separator and whether array indexes use brackets or the separator.

  3. 3

    Pick flat JSON or a key = value list as the output format.

  4. 4

    Click Flatten JSON, then copy the result or download it.

About the JSON Flattener

The ByteTools JSON Flattener turns a deeply nested JSON document into a single-level object whose keys are full paths, such as user.address.city or items[0].price. Nested objects and arrays are walked recursively so every leaf value ends up with one unambiguous key you can read, grep or feed into another system.

It is useful when you need JSON in a tabular shape: loading records into a spreadsheet, building translation or config files, mapping API fields for an ETL job, or diffing two payloads line by line. You can pick the key separator, switch array indexes between items[0] and items.0, and output either flat JSON or a plain key = value list.

Flattening runs 100% locally in your browser with JavaScript. Your JSON is never uploaded, logged or stored, so it is safe to use on production API responses, private configuration and customer data.

Frequently asked questions

What does it mean to flatten JSON?

Flattening replaces nesting with path-style keys. Instead of an object inside an object, you get one level where the key spells out the whole route to the value, like user.address.city. That makes JSON far easier to put in a spreadsheet, compare or search.

How are arrays handled when flattening JSON?

Each element gets its index in the key. With bracket notation you see items[0].name and items[1].name; switch to separator notation and the same paths become items.0.name and items.1.name. Pick whichever your target system expects.

Can I flatten JSON back into nested form again?

Yes. Use the JSON Unflattener with the same separator and your dot-notation keys expand back into the original nested structure, including arrays where the path segments are numeric.

What happens if a key already contains a dot?

The dot inside the original key becomes indistinguishable from a path separator, so round-tripping that key is ambiguous. If your data has dots in key names, choose a different separator such as a slash before flattening.

Is my JSON uploaded anywhere?

No. The whole conversion happens in your browser with JavaScript. Nothing is sent to a server, logged or stored, so confidential payloads stay on your machine.

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