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Data

JSON Viewer

Explore JSON with collapsible tree view and structure info

What is JSON?

JSON data structures can grow remarkably complex in real-world applications. A single API response from a service like GitHub, Stripe, or Elasticsearch can contain hundreds of nested objects and arrays spanning dozens of levels. Reading this data as flat text — even pretty-printed — quickly becomes unmanageable because you lose track of which closing brace matches which opening brace and where you are in the hierarchy.

A JSON tree viewer solves this by rendering the data as a collapsible, hierarchical outline — similar to a file explorer in an IDE. Each object and array becomes a node you can expand or collapse with a click. This transforms a wall of text into a navigable structure where you can open the branches you care about and hide everything else, maintaining spatial awareness of where each piece of data sits in the overall hierarchy.

Tree viewers are particularly valuable during the exploratory phase of development — when you receive an API response for the first time and need to understand its shape before writing code to consume it. Rather than reading documentation (which may be outdated) or scrolling through raw JSON, you can interactively drill into the structure, note which fields exist, check how arrays are nested, and identify the paths you need to reference in your application code.

How it works

The viewer parses the input JSON into an in-memory tree using the browser's native JSON.parse(), then recursively renders each node as a collapsible UI element. Objects are rendered with their keys listed vertically, each key followed by its value (which may itself be a nested object or array). Arrays are rendered with numeric indices. Primitive values (strings, numbers, booleans, null) are displayed as leaf nodes with type-specific color coding.

The collapse and expand mechanism uses component-level state to track which nodes are open. When you collapse a node, its children are hidden from the DOM but remain in memory, so re-expanding is instant. The viewer also provides "Expand All" and "Collapse All" controls for quickly opening or closing the entire tree, which is useful when you want to switch between a high-level overview and a detailed inspection.

Structural metadata — the key count for objects and item count for arrays — is computed during the initial render pass and displayed as inline badges next to each node's toggle control. These counts are always visible regardless of whether the node is expanded or collapsed, giving you a quantitative sense of the data shape at every level without requiring you to expand and manually count.

How to use this tool

  1. Paste your JSON data into the input area. The tree renders automatically as soon as valid JSON is detected.
  2. Click the arrow or toggle next to any object or array to expand or collapse it. Expanded nodes show their children indented below; collapsed nodes show just the key count or item count badge.
  3. Use "Expand All" to open the entire tree for full inspection, or "Collapse All" to return to the top-level overview. This is especially useful for large payloads where you want to get oriented before drilling in.
  4. Observe the color-coded values: strings, numbers, booleans, and null each have distinct colors so you can quickly identify data types at a glance.
  5. Click on a node to select it and copy its subtree as valid JSON. This lets you extract a specific branch for use in other tools or for pasting into code.

Examples

Exploring a GitHub API repository response

The /repos endpoint returns a deeply nested object with owner details, license information, permissions, and more. The tree viewer lets you collapse sections like "owner" and "license" to focus on the fields you care about — like "default_branch," "open_issues_count," or "topics" — without scrolling past dozens of unrelated fields.

Understanding a Stripe payment intent object

Payment intents contain nested charges, payment methods, metadata, and error objects. Expanding just the "charges.data[0].payment_method_details" branch reveals the card brand, last four digits, and funding type without wading through the full 200+ field response.

Inspecting an Elasticsearch query result

Elasticsearch responses wrap results in several layers of metadata — hits.hits[].source contains the actual documents, while aggregations can be deeply nested. The tree viewer lets you collapse the metadata scaffolding and focus on the source documents or specific aggregation buckets.

Reviewing a complex application config file

A monorepo configuration JSON might contain build settings, environment overrides, feature flags, and dependency maps. Collapsing completed sections and expanding only the one you are editing keeps the cognitive load manageable, much like folding code in an IDE.

About this tool

Paste any JSON to explore it as an interactive tree. Collapse and expand objects and arrays, see the number of keys in objects and items in arrays at a glance, and navigate deeply nested structures with ease — all client-side.

Common use cases

  • • Exploring complex API responses with deeply nested objects and arrays
  • • Getting a quick overview of JSON structure by collapsing sections you don't need
  • • Inspecting data shapes when building frontend components that consume JSON APIs
  • • Reviewing database exports or configuration files with readable formatting

Frequently asked questions

How is this different from the JSON Formatter?
The JSON Formatter shows formatted text output. The JSON Viewer renders an interactive tree where you can collapse and expand individual objects and arrays, making it much easier to navigate large or deeply nested structures.
Can I see the size of objects and arrays?
Yes. Each object shows the number of keys and each array shows the number of items right next to the collapse toggle, so you can understand the structure at a glance without expanding everything.
Does this tool modify my JSON?
No. The viewer is read-only — it parses and displays your JSON in a tree format without modifying the data. Use the JSON Formatter if you need to reformat the output.
How deep can the nesting go?
The tree viewer handles JSON nested to any depth. Each level is indented and collapsible independently, so you can expand only the branches you care about. For extremely deep structures (50+ levels), the tree remains functional but you may want to use the JSON Search tool to jump directly to the path you need.
Can I copy a subtree from the viewer?
Yes. You can click on any node in the tree to select it and copy that subtree as valid JSON. This is useful when you need to extract a nested object or array from a larger payload without manually editing the raw text.
What do the badges next to objects and arrays mean?
Objects display a badge showing the number of keys (e.g., "{3 keys}") and arrays show the number of items (e.g., "[5 items]"). These counts appear even when the node is collapsed, giving you a structural overview without expanding every branch. This is particularly helpful for understanding the shape of unfamiliar API responses at a glance.