JSON Flatten

What is JSON Flatten

Last reviewed: April 18, 2026

JSON (JavaScript Object Notation) is a lightweight, human-readable data format used almost everywhere on the web for APIs, config files, and log output.

JSON Flatten converts nested JSON into a single-level map where each key is a dotted path plus bracketed array indices (`users[0].tags[1]`).

It's perfect for diffing complex payloads, feeding configuration into flat key/value stores, and building query strings from nested structures.

Why use it

• Diff two JSON payloads key-by-key.
• Feed nested config into flat KV stores.
• Build dotted query strings.
• Compare API responses across versions.
• Simplify Jq-style path navigation.

Features

• Dot or custom separator
• Bracketed array indices
• Preserves empty containers
• Reversible with Unflatten
• JSON Flatten is handled entirely in-browser

How to use JSON Flatten

1. Paste JSON. Nested object or array-of-objects.
2. Set separator. Default `.` or choose your own.
3. Run. Copy the flat map.

Example (before/after)

{
  "user": { "id": 1, "tags": ["admin", "ops"] }
}

{
  "user.id": 1,
  "user.tags[0]": "admin",
  "user.tags[1]": "ops"
}

Common errors

FAQ

Related tools

Pair with JSON Unflatten and diff tools. You can also browse the full Data Converters category for more options.