Facing a JSON document you have never seen is like walking into a building at night: you know there are rooms, but you cannot tell how many or where until the lights come on. Reading the raw text works, but the shape of the data — its vocabulary of keys, its depth, where arrays repeat — hides behind the syntax. For a third-party API response, a log export or a config dump, you need the map, not the text.
Extract JSON Keys produces that map in one click. It walks the entire document and lists every key, either as a deduplicated vocabulary of field names or as full dot paths that show exactly where each field lives. Sort alphabetically or keep encounter order, include array indices when positions matter, and export as one-per-line, a JSON array, or CSV for a spreadsheet. Counts are reported live, everything runs in your browser, and the output feeds straight into schema documentation, mapping work or quick comprehension.