Tiny Toolkit

JSON Flattener

Transform a deeply nested JSON object into a flat, single-level structure using dot-notation keys — for example, {"user": {"name": "Alice"}} becomes {"user.name": "Alice"}. Useful for writing queries against nested data in analytics tools, mapping JSON fields to database columns, or simplifying complex API responses for processing. Arrays are indexed numerically in the output keys.

All processing happens in your browser. No data is sent to any server.

Frequently Asked Questions

What does flattening JSON mean?
Flattening takes a deeply nested JSON object and produces a new object where all values are at the top level. Nested keys are joined with a separator, so {"a":{"b":1}} becomes {"a.b":1}.
How are arrays handled?
Array indices are used as key segments, so an array item at index 0 becomes part of the key path. For example, {"items":[{"name":"x"}]} flattens to {"items.0.name":"x"}.
Can I change the separator from a dot to something else?
Yes. The separator dropdown lets you choose a dot (.), underscore (_), or slash (/). Choose the separator that does not conflict with your existing key names.
What is the key count stat?
Input key count is the total number of keys across all levels of the original nested object. Output key count is the number of flat keys produced. These help you verify the flattening captured every value.

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