JSON Key Extractor

How to use the json key extractor

1. Paste your JSON.
2. Read the list of key paths, types and counts.
3. Look for fields with two types or an unexpected count.

About this tool

This produces the shape of a document rather than its contents: every distinct key path, the type found there, and how many times it occurs.

Array indices collapse to <code>[]</code>, which is what makes the output usable. A thousand-element array would otherwise produce a thousand nearly identical paths; collapsed, it produces one line saying the field exists a thousand times.

The occurrence count and the type together are what make this useful for finding inconsistency. A field that shows two types — <code>string | number</code> — is a field some producer is writing differently, and that is usually a bug waiting to happen in whatever consumes it. A field appearing fewer times than its siblings is optional, whether or not anyone documented it that way.

Everything happens in the page. JSON commonly carries API keys, personal records and internal identifiers, so nothing here is uploaded, logged or sent to a server — which is exactly why a browser tool is the right place to inspect it.

Common uses

• Documenting the shape of an undocumented API response.
• Finding fields whose type is inconsistent between records.
• Working out which fields are optional in a dataset.

Frequently asked questions

Why do array indices show as []?

So a large array produces one path rather than thousands of near-identical ones. The count tells you how many times the field actually occurred.

What does 'string | number' mean?

That field holds different types in different records. It usually means something is writing the data inconsistently, which tends to break consumers later.

Is this a JSON schema?

No. It is a plain inventory of paths and types, not a validating schema document.