Developer Formatting

JSON flattener

Input

{"user":{"name":"Ada","tags":["a","b"]}}

What to do

Indent

Output

{
  "user.name": "Ada",
  "user.tags[0]": "a",
  "user.tags[1]": "b"
}

Processed in your browser · nothing is uploaded

Local · empty containers survive the round trip

Turns a nested structure into a single object keyed by dotted path — `user.name`, `user.tags[0]` — and turns it back again.

How to use the json flattener

1 Paste your input. The result appears immediately.

2 Pick the operation you want.

3 Copy the result, or save it as a file.

Flattened JSON is what a lot of systems actually want: translation files, feature-flag stores, environment configuration and analytics payloads are all flat key-value maps, and a nested document has to be flattened to fit. The round trip is lossless for ordinary data, with one edge worth knowing about — an empty array or object has no leaf to flatten into, so it is preserved as an explicit empty value rather than vanishing, which is exactly what lets unflattening give back what you started with.

Questions

What notation does it use? −

Dots for object keys and square brackets for array indices, so `a.b[0].c`. That is the convention most config systems use.

Is the round trip lossless? +

Why would I flatten JSON? +

What if a key contains a dot? +

Is my data sent anywhere? +

Sources

ECMA-404 — the JSON data interchange syntax MDN — JSON.parse()

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