JSON Viewer
Visualize JSON as an interactive collapsible tree. Click nodes to expand or collapse.
Why Use a JSON Tree Viewer?
Large JSON files with deeply nested structures are difficult to read as raw text. A tree viewer collapses nodes at each level, letting you focus on the parts you care about without scrolling through thousands of lines.
Tree viewers are especially useful when working with API responses, configuration files, and data exports that contain multiple levels of nesting.
Navigating JSON Structures
In a tree view, objects are shown as collapsible nodes with their key count. Arrays display their element count. Primitive values (strings, numbers, booleans) are shown inline with color coding to make type identification instant.
This makes it immediately obvious whether a field contains a nested object, an array of items, or a primitive value — something that requires careful reading in raw JSON.
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Frequently Asked Questions
What is a JSON tree viewer?
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A JSON tree viewer renders JSON as an expandable/collapsible hierarchical tree, making it easy to navigate complex nested structures without reading raw text.
Can I collapse deeply nested nodes?
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Yes. Click any node's toggle arrow to collapse or expand it. Nodes deeper than 2 levels are collapsed by default to keep the initial view manageable.
What types does the viewer support?
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The viewer handles all JSON types: objects (shown with key count), arrays (shown with element count), strings (green), numbers (orange), booleans (blue), and null (gray).
Does this JSON viewer work offline?
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Yes. FastDevTool is a Progressive Web App (PWA) with a service worker. Once you have visited the page, it works fully offline — no internet connection required.