What does flattening do to arrays?

Array elements become indexed path segments. In dot notation an element looks like items.0.name; in bracket notation it looks like items[0].name. Both point to the same value.

What is the depth limit for?

If you set a max depth, the flattener stops descending past that level and keeps the remaining sub-structure as a JSON value at that key. Leave it blank to flatten all the way to the leaves.

How are empty objects and arrays handled?

Empty objects and empty arrays are kept as leaf values ({} or []) so no information is lost. Only non-empty containers are expanded into deeper keys.

Is my JSON sent to a server?

No. Parsing and flattening run entirely in your browser with local JavaScript. Nothing you paste is uploaded or logged.

Nested JSON Flattener

Flatten nested LLM JSON into flat keys

Structured LLM outputs and tool-call payloads nest objects inside arrays inside objects. That’s painful to map into a spreadsheet, a form, or a flat config. This tool turns any nested JSON into a single-level key-value map where each key is the full path to a leaf value — in either dot notation (a.b.0.name) or bracket notation (a.b[0].name) — with an optional depth limit.

How flattening works

The flattener walks the JSON recursively. Whenever it hits a leaf — a string, number, boolean, null, an empty object, or an empty array — it records the accumulated path as a key and the leaf as the value. Non-empty objects and arrays are expanded: object keys are appended as path segments and array elements are appended as numeric indices. If you set a maximum depth, descent stops at that level and the remaining structure is kept intact as a JSON value, so nothing is lost. The result is one flat object you can read top to bottom.

Tips and examples

Use dot notation when you’ll feed the keys into tools that expect a.b.0 paths; use bracket notation when you want valid JavaScript-style accessors.
Flatten a tool-call arguments object to quickly diff two responses field by field.
Set a shallow depth (1 or 2) to get a high-level overview of a huge payload before drilling in with the JSON Pointer Extractor.
Empty containers are preserved as {} / [] so the flattened map round-trips the original structure faithfully.