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Parsed JSON will appear here

What Is JSON Viewer?

JSON (JavaScript Object Notation) is a lightweight data-interchange format widely used across web APIs, configuration files, and data storage. ToolRunner's JSON Viewer lets you paste, upload, or edit raw JSON and instantly see it rendered as a formatted tree, searchable text, or sortable table — all without sending a single byte to any server.

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Key Features

  • Real-time parsing with instant syntax error detection and line/column indicators
  • Three output views: Tree, Text (syntax-highlighted), and Table for arrays of objects
  • One-click Prettify and Minify to format or compress your JSON
  • Built-in search across both the raw input and the rendered output
  • Drag-to-resize split panes and a distraction-free fullscreen mode
  • File upload support for .json files up to 20 MB
  • Download formatted JSON or copy it to your clipboard instantly

How to Use

Paste your JSON into the left editor or click Upload to load a file. The viewer parses it in real time and displays the result on the right. Switch between Tree, Text, and Table views using the tabs. Use the Expand/Minify buttons to prettify or compress the data, and the search bars to locate specific keys or values. Drag the center divider to adjust pane widths, or click Full to enter fullscreen mode.

Why Use a Browser-Based JSON Viewer?

Unlike online tools that upload your payload to a remote server, ToolRunner processes everything locally with JavaScript. This means confidential API responses, tokens, and configuration files never leave your machine. It also means zero network latency — parsing happens the instant you type.

Common Use Cases

  • Debugging REST or GraphQL API responses during development
  • Inspecting and editing package.json, tsconfig.json, or other config files
  • Validating webhook payloads and event data
  • Formatting minified JSON for code reviews or documentation
  • Exploring large datasets with the Table view for quick analysis

Frequently Asked Questions

Is my JSON data sent to any server?
No. All parsing and rendering happen entirely in your browser using JavaScript. Your data never leaves your device.
What is the maximum file size supported?
You can upload JSON files up to 20 MB. For very large files, performance depends on your browser and device memory.
Can I use this tool offline?
Yes. Once the page has loaded, the JSON Viewer works without an internet connection because all processing is client-side.
Does it support JSON with comments or trailing commas?
The viewer uses the standard JSON.parse method, which follows the strict JSON specification. Comments and trailing commas will be reported as syntax errors.
How do I fix a JSON syntax error?
When a syntax error is detected, a red banner appears at the bottom showing the exact line and column. Click 'Show me' to jump directly to the error location in the editor.