Auto-format JSON with syntax highlighting and collapsible trees
JSON Viewer is an essential browser extension for developers who work with JSON data daily. It automatically detects and formats JSON content in your browser, transforming ugly minified JSON into beautifully formatted, syntax-highlighted, and navigable tree structures. With over 2 million users and a 4.7/5 rating, it's become the standard tool for viewing JSON in the browser.
Whether you're testing API endpoints, debugging backend responses, inspecting webhook payloads, or reviewing configuration files, JSON Viewer makes the data instantly readable. Instead of staring at a wall of text like {"user":{"id":123,"name":"John","preferences":{"theme":"dark","lang":"en"}}}, you see a properly indented, color-coded structure where you can collapse and expand nested objects.
The extension works automatically—no configuration needed. Navigate to any URL that returns JSON (like an API endpoint), and JSON Viewer instantly prettifies the response with syntax highlighting. Objects are color-coded (keys in purple, strings in green, numbers in blue), making it easy to scan complex data structures at a glance. Nested arrays and objects can be collapsed to hide details you don't need, letting you focus on specific parts of large JSON payloads.
JSON Viewer also includes powerful features like raw mode toggle (switch between formatted and original JSON), dark/light theme support, error detection (highlights syntax errors with helpful messages), and one-click copy for quickly grabbing formatted JSON. Best of all, it's completely free with no premium tiers—all features are available to everyone.
Automatically detect and prettify JSON responses with proper indentation and spacing for maximum readability.
Color-coded JSON elements (keys, strings, numbers, booleans) make complex structures easy to scan and understand.
Collapse and expand nested objects and arrays to hide unnecessary details and focus on specific data sections.
Switch between formatted pretty-print and raw JSON with a single click for comparison or debugging.
Choose between dark and light themes to match your workflow and reduce eye strain during long debugging sessions.
Instantly identify syntax errors with highlighted problem areas and helpful error messages for quick fixes.
Visit the Chrome Web Store and install JSON Viewer. Atlas Browser supports all Chromium extensions seamlessly.
Open any API endpoint or URL that returns JSON data (like https://api.github.com/users/octocat).
JSON Viewer automatically formats the response with syntax highlighting and collapsible trees—no configuration needed.
Click the arrows next to objects and arrays to collapse or expand nested data, making it easier to navigate large payloads.
Right-click the extension icon to access settings for themes, indentation size, and other display preferences.
Stop squinting at minified JSON. Instantly visualize API responses with proper formatting and color coding for faster debugging.
Works automatically out of the box. No setup, no configuration files, no learning curve—just install and start viewing formatted JSON.
Collapsible tree structure makes it trivial to explore massive JSON responses without getting lost in nested data.
No premium tiers, no subscriptions, no paywalls. All features are free forever for all users.
JSON Viewer is a free browser extension that automatically formats and prettifies JSON responses in your browser, making them easier to read with syntax highlighting, collapsible trees, and error detection. It's essential for API development and debugging.
Yes, JSON Viewer is completely free with no premium tiers or subscriptions. All features—including syntax highlighting, collapsible trees, themes, and error detection—are available to all users at no cost.
Install JSON Viewer from the Chrome Web Store. Atlas Browser supports all Chromium extensions, so installation is identical to Chrome. Once installed, it automatically formats any JSON content you view in the browser.
Yes, JSON Viewer automatically detects and formats JSON responses from APIs, making it essential for API development and debugging. It works with any endpoint that returns JSON data—REST APIs, GraphQL, webhooks, and more.
Yes, JSON Viewer includes one-click copy functionality. You can copy the formatted JSON with proper indentation, or switch to raw mode to copy the original unformatted version.
Yes, JSON Viewer works entirely in your browser without requiring internet connectivity. It can format local JSON files or API responses even when you're offline.
Join 2 million developers who format JSON instantly with syntax highlighting and collapsible trees.