UD5 Toolkit
Browser Font Stacks Explorer - Online Defaults Per OS
See which fonts map to generic families (serif, sansβserif, monospace) on different operating systems. A handy reference.
Browser Feature Support Detector - Online Check Your Device
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Total TestsNo features match your search or filter.
Try adjusting your criteria.Frequently Asked Questions
Browser feature detection is the practice of checking whether a specific web API, CSS property, or JavaScript feature is available in the user's current browser. Instead of guessing based on browser name and version (user-agent sniffing), feature detection directly tests the capability, giving reliable results regardless of the browser.
Feature detection allows developers to implement progressive enhancement and graceful degradation. You can provide rich experiences for modern browsers while ensuring your site still works on older ones. It's more reliable than browser sniffing and helps avoid broken functionality on unsupported platforms.
This tool performs real-time, live detection using JavaScript and CSS APIs directly in your browser. Each feature is tested programmatically at runtime. Results are 100% accurate for your current browser, version, and settings. Features marked "Partial" may have limited availability (e.g., Service Workers require HTTPS).
"Partial" indicates the API exists but may have limitations. For example, Service Workers require a secure HTTPS connection to function, SharedArrayBuffer needs cross-origin isolation headers, and Cookies may be blocked by privacy settings even if the API exists. Always read the feature description for specific notes.
Use simple
if statements in JavaScript (e.g., if ('geolocation' in navigator)) or @supports in CSS (e.g., @supports (display: grid)). Libraries like Modernizr also provide comprehensive detection. The key principle: test the feature, don't guess the browser.Major browsers (Chrome, Firefox, Safari, Edge) release updates every 4-6 weeks. New web platform features are continuously added. We recommend re-checking your browser's capabilities periodically, especially after browser updates, as support for cutting-edge features like AVIF images or Container Queries can change rapidly.
Common gaps include AVIF image format (newer format, Safari added support in 2023), Web Bluetooth (Chromium-only), Payment Request API (varies by region), and SharedArrayBuffer (requires special server headers). Safari historically lags behind Chrome/Firefox on some newer APIs. Use this tool to identify exactly what your browser supports.
Compression Streams API Demo - Online Gzip/Deflate Raw
Compress and decompress text using the browser's native Compression Streams API. See the binary output size.
CSS Compatibility Linter - Online Check Browser Support
Paste your CSS and see warnings for properties that have limited browser support. Links to CanIUse. Modernize safely.
Emoji Version Detector - Online Check Unicode Support
See how your browser renders emojis from different Unicode versions. Detect gaps in your system's emoji font support.
Permissions Query API Demo - Online Check All APIs
Query the permission state of camera, microphone, geolocation, and more. See the response and learn the API.
Pointer Events Playground - Online Mouse, Touch & Pen
Unified input demo: see pressure, tilt, and type from any pointer. Compare pointerType values. Essential for drawing apps.
User Agent Style Sheet Explorer - Online See Default CSS
Browse the builtβin styles that browsers apply to HTML elements. Understand why your page looks different. Static reference.
Screen Wake Lock Tester - Online Keep Screen On
Toggle a screen wake lock to prevent the device from dimming or sleeping. See the lock state and learn the API.
ImageDecoder API Demo - Online Progressive Decode
Decode an image progressively using the ImageDecoder API. See partial results and metadata. Modern alternative to <img>.
WebCodecs Video Frame Reader - Online Decode & Display
Decode individual video frames from a local file using the VideoDecoder API. Step through frames. Cuttingβedge browser feature.
Web HID Explorer - Online List & Read HID Devices
Request HID devices and list them. Read input reports and send output. For custom hardware and controllers.
Web OTP API Demo - Online AutoβRead SMS Codes
Demonstrate how the Web OTP API automatically reads oneβtime codes from SMS (mobile). Simulation with a fake SMS input.
Web Locks API Demo - Online Resource Coordination
Acquire and release locks across tabs. Prevent race conditions in IndexedDB or localStorage. Visual queue and lock state.
Gamepad API Tester - Online Visual Controller Check
Connect a gamepad and see all button presses and axis movements visually. Check that every input is detected correctly.
Vibration API Demo - Online Test Haptic Feedback
Trigger different vibration patterns on mobile devices. Test if your phone supports haptic feedback. Simple demo.
Battery Status API Viewer - Online Check Level
See your device's battery level, charging status, and discharge time using the Battery Status API. Fun utility.
Screen Orientation API Tester - Online Lock & Check
Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.
Popover API Demo - Online NoβJS Tooltips & Menus
Test the new HTML popover attribute for creating accessible tooltips, menus, and dialogs without JavaScript. Copy code snippets.
Clipboard API Tester - Online Read & Write Sandbox
Experiment with the Async Clipboard API: read/write text and images from the clipboard. Verify permissions and see demo code.
Web Share API Tester - Online Demo & Code
Test the Web Share API by sharing text, links, and files directly from the browser. Check compatibility and see example code.
API Status Checker - Online Test Endpoint & Response
Enter an API URL and quickly check its HTTP status code and response time. See response headers and body. Browser fetch.
Instant Image Slideshow - Online Local Photo Player
Select a folder of images and start a fullβscreen slideshow right in your browser. Adjust interval and transition. No upload.
Tab Counter & Memory Estimator - Online Window Stats
See how many tabs you have open and estimate memory usage based on navigator object. Fun productivity check.
HTTP Request Composer - Online Build & Send Requests
Pick a method, URL, headers, and body, then send an HTTP request directly from your browser. Debug APIs easily.
Browser Fingerprint Viewer - Online See Your Unique ID
Generate a hash showing how trackers can fingerprint your browser (canvas, WebGL, fonts). Educational and privacyβaware.
Cookie String Parser - Online Decode & Format Browser Cookies
Paste a raw cookie string and see a formatted keyβvalue table. Debug session cookies and understand flags. Runs in browser.
Random JSON Generator - Online Create Sample API Responses
Generate random JSON data with customizable fields (users, products, orders). Useful for frontend mocking. All local.
Screen Recorder - Online Record Browser Tab & Download WebM
Record your screen, application window, or browser tab directly using the Screen Capture API. Download as WebM. All local.
Keyboard Shortcuts Viewer - Online Your Browser & OS Keys
Display a dynamic list of keyboard shortcuts for the current browser and operating system. Filter by category. Keep it open for reference.
GraphQL Playground - Online Query & Schema Explorer
Execute GraphQL queries against any endpoint with variables and headers. Explore schema via introspection. All requests made directly from your browser.