UD5 Toolkit
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.
Tag: API Request Builder
63+ toolsGraphQL 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.
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.
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.
View Transitions API Demo - Online Smooth Page Switch
See the View Transitions API in action. Cross‑fade and morph between two states. Copy the JavaScript starter code.
Random JSON Generator - Online Create Sample API Responses
Generate random JSON data with customizable fields (users, products, orders). Useful for frontend mocking. All local.
Popover API Demo - Online No‑JS Tooltips & Menus
Test the new HTML popover attribute for creating accessible tooltips, menus, and dialogs without JavaScript. Copy code snippets.
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.
Idle Detection API Demo - Online User Activity Monitor
Request permission and detect when the user is idle (away from keyboard). See screen lock state. For native‑like apps.
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.
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.
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.
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.
Background Sync API Tester - Online Offline Queue
Register a one‑off background sync and see it fire when connectivity returns. Debug service worker sync logic.
Web OTP API Demo - Online Auto‑Read SMS Codes
Demonstrate how the Web OTP API automatically reads one‑time codes from SMS (mobile). Simulation with a fake SMS input.
Screen Orientation API Tester - Online Lock & Check
Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.
Gamepad Tester - Online Button & Axis Visualizer
Connect a game controller and see every button press, axis movement, and vibration test. Uses the Gamepad API.
FedCM Demo - Online Federated Credential Management
Experiment with the Federated Credential Management API. Simulate a sign‑in flow without third‑party cookies. Privacy‑first.
Prioritized Task Scheduler Demo - Online scheduler.postTask()
Schedule tasks with user‑visible, user‑blocking, or background priority. See execution order and delays. Modern web perf.
Web Notification Tester - Online Permission & Display
Check notification permission, request it, and send a test notification. Verify icon, body, and tag. Debug web push.
Network Information API Checker - Online Downlink Speed
Display your effective connection type (4g, 3g, etc.) and downlink speed using the Navigator API. Adapt your app accordingly.
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 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.
Built-in Translation API Demo - Online On‑Device Translate
Test the experimental Translation API to translate text between languages directly in the browser, without cloud calls. Check support and copy the JavaScript starter.
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. Cutting‑edge browser feature.
Shared Storage API Demo - Online Cross‑Site Data
Write to shared storage and run a worklet to process data. Learn the privacy‑preserving alternative to third‑party cookies.
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.
Ambient Pressure Sensor Demo - Online Barometer
Read the ambient atmospheric pressure in hPa using the Pressure Sensor API (if available). Real‑time graph.
Navigation API Playground - Online Single‑Page Router
Intercept and manage navigations without reloading. Test transition handling and URL updates. The future of client‑side routing.
Resize Observer Playground - Online Watch Element Size
Drag to resize a box and see the Resize Observer callback fire. Get contentRect and borderBoxSize. Learn the API.
Bluetooth Battery Monitor - Online Read Device Levels
Connect to a BLE device and read its Battery Service characteristic. See the charge level in a gauge.
Font Access API - Online Browse Local Fonts
Enumerate all fonts installed on your device and see a real‑time preview. Useful for design tools. Permission required.
File Handle API Demo - Online Persistent File Access
Use the File System Access API with file handles for persistent read/write. Learn incremental saving patterns.
Content Indexing API Test - Online Add to Device's Media Feed
Test the Content Indexing API to add a page to the device's content feed. See how your PWA integrates with the OS.
Web Share Level 2 Tester - Online Share Files
Test sharing multiple files (images, PDFs) using the Web Share API. Check if the browser supports file sharing. Demo page.
Picture‑in‑Picture Tester - Online Float Video Anywhere
Open a test video in Picture‑in‑Picture mode. Control entering and leaving PiP. Copy the code snippet for your own app.
Wake Lock API Tester - Online Prevent Screen Sleep
Request and release a screen wake lock to keep the device awake. See the lock state in real time. Perfect for recipes or presentations.
Cookie Store API Tester - Online Async Cookie Read/Write
Read, write, and delete cookies using the modern Cookie Store API. Monitor change events. No more document.cookie parsing.
Launch Handler API Demo - Online Control App Launch Behavior
Configure how your PWA launches: focus existing or create new. Test with the launch_handler manifest field.
Broadcast Channel API Demo - Online Cross‑Tab Communication
Open the same page in two tabs and send messages between them. See real‑time cross‑tab communication. Learn the API.
API Request Builder - Online Test REST Endpoints
Select HTTP method, set headers, and body. Send requests and see the full response. Lightweight Postman alternative.
Web Animations API Sandbox - Online JS Animation Editor
Write JavaScript using element.animate() and see the result in a live preview. Compare with CSS keyframes. Debugger included.
Private State Token Demo - Online Anti‑Fraud Test
Issue and redeem Private State Tokens (formerly Trust Tokens). Understand how they help detect bots without cookies.
File System Access API Demo - Online Open & Save Files
Test the modern File System Access API. Open a file, modify it, and save back to disk. All sandboxed in browser.
Navigation Timing API Viewer - Online Page Load Breakdown
See your current page load broken down into DNS, TLS, request, and DOM phases. Understand where time is spent.
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.
Mutation Observer Tester - Online DOM Change Watcher
Modify the DOM via buttons and see MutationRecords logged. Understand childList, attributes, and subtree options.
Media Session API Demo - Online Now Playing Widget
Set media metadata and play/pause controls for the OS media widget. Test action handlers. Perfect for web audio apps.
Linear Acceleration Sensor - Online Motion Visualizer
Visualize real‑time linear acceleration (excluding gravity). Watch the 3D vector graph move as you shake the device.
Contact Picker API Demo - Online Select & Read Contacts
Pick a contact from the device’s address book (mobile). Read name, email, and phone. All permission‑based. Privacy safe.
Navigation Timing API Viewer - Online Page Load Breakdown
See your current page load broken down into DNS, TLS, request, and DOM phases. Understand where time is spent.
Constraint Validation API Tester - Online Form Debug
Test required, pattern, minlength etc. See validity states and custom error messages. Learn browser‑native validation.
Web USB Console - Online Claim & Talk to USB Device
Request a USB device and communicate with it using the Web USB API. See vendor and product IDs. Experimental.
EyeDropper API - Online Pick Any Screen Color
Use the EyeDropper API to sample a color from anywhere on your screen. Click, select, and copy the hex. No extensions needed.
Resource Timing Viewer - Online See All Asset Loads
List all resources loaded by the current page and their detailed timing breakdown. In‑browser waterfall.
Selection & Range API Demo - Online Get/Set Selection
Select text and see the Selection object properties. Create ranges programmatically. Understand how rich‑text editors work.
Browser Feature Support Detector - Online Check Your Device
See a comprehensive table of which modern web APIs your current browser supports. Includes WebGPU, AVIF, and more.
Periodic Background Sync Registration - Online PWA Tool
Register a periodic background sync with a minimum interval. See the registration state and tags. Keep content fresh.