JSON Flattener

JSON Flattener collapses deeply nested JSON into a single flat object whose keys are full paths, turning structures like {"user":{"name":"Ada"}} into {"user.name":"Ada"}.

This makes nested data far easier to scan, diff, search and load into tools that expect flat key-value pairs, such as spreadsheets, environment files, translation catalogues and analytics pipelines.

Paste any valid JSON and the flattened result appears instantly.

You control the delimiter that joins nested keys — a dot is the default, but you can switch to a slash, a colon or anything that suits your target system.

Arrays can be written with simple index keys like items.0.name, or with bracket notation like items[0].name when you need JSONPath-style output.

Empty objects and empty arrays are preserved as leaf values rather than being silently dropped, so no information is lost in the conversion, and null, boolean and number leaves keep their original types.

If the input is not valid JSON, the tool explains the parse error in plain language instead of failing silently, so you can fix the problem quickly.

The whole process runs locally in your browser — your data is never uploaded or stored — which makes it safe for configuration files and other sensitive payloads, and a copy button puts the flattened JSON one click away.