UD5 Toolkit
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.
Tag: API Request Builder
63+ toolsClipboard 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.
Vibration API Demo - Online Test Haptic Feedback
Trigger different vibration patterns on mobile devices. Test if your phone supports haptic feedback. Simple demo.
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.
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.
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.
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. Cuttingâedge browser feature.
Screen Orientation API Tester - Online Lock & Check
Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.
Web OTP API Demo - Online AutoâRead SMS Codes
Demonstrate how the Web OTP API automatically reads oneâtime codes from SMS (mobile). Simulation with a fake SMS input.
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.
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.
Popover API Demo - Online NoâJS Tooltips & Menus
Test the new HTML popover attribute for creating accessible tooltips, menus, and dialogs without JavaScript. Copy code snippets.
Random JSON Generator - Online Create Sample API Responses
Generate random JSON data with customizable fields (users, products, orders). Useful for frontend mocking. All local.
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.
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.
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.
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.
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.
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.
FedCM Demo - Online Federated Credential Management
Experiment with the Federated Credential Management API. Simulate a signâin flow without thirdâparty cookies. Privacyâfirst.
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 nativeâlike apps.
View Transitions API Demo - Online Smooth Page Switch
See the View Transitions API in action. Crossâfade and morph between two states. Copy the JavaScript starter code.
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.
Gamepad Tester - Online Button & Axis Visualizer
Connect a game controller and see every button press, axis movement, and vibration test. Uses the Gamepad API.
Built-in Translation API Demo - Online OnâDevice 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.
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.
API Request Builder - Online Test REST Endpoints
Select HTTP method, set headers, and body. Send requests and see the full response. Lightweight Postman alternative.
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.
Navigation API Playground - Online SingleâPage Router
Intercept and manage navigations without reloading. Test transition handling and URL updates. The future of clientâside routing.
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.
Background Sync API Tester - Online Offline Queue
Register a oneâoff background sync and see it fire when connectivity returns. Debug service worker sync logic.
PictureâinâPicture Tester - Online Float Video Anywhere
Open a test video in PictureâinâPicture mode. Control entering and leaving PiP. Copy the code snippet for your own app.
Web Notification Tester - Online Permission & Display
Check notification permission, request it, and send a test notification. Verify icon, body, and tag. Debug web push.
Shared Storage API Demo - Online CrossâSite Data
Write to shared storage and run a worklet to process data. Learn the privacyâpreserving alternative to thirdâparty cookies.
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.
Contact Picker API Demo - Online Select & Read Contacts
Pick a contact from the deviceâs address book (mobile). Read name, email, and phone. All permissionâbased. Privacy safe.
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.
Prioritized Task Scheduler Demo - Online scheduler.postTask()
Schedule tasks with userâvisible, userâblocking, or background priority. See execution order and delays. Modern web perf.
Web Serial Terminal - Online Connect to Microcontroller
Connect to a serial device (Arduino, etc.) via the Web Serial API. Send and receive text. No native app needed.
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.
Linear Acceleration Sensor - Online Motion Visualizer
Visualize realâtime linear acceleration (excluding gravity). Watch the 3D vector graph move as you shake the device.
Font Access API - Online Browse Local Fonts
Enumerate all fonts installed on your device and see a realâtime preview. Useful for design tools. Permission required.
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.
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.
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.
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.
Ambient Pressure Sensor Demo - Online Barometer
Read the ambient atmospheric pressure in hPa using the Pressure Sensor API (if available). Realâtime graph.
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.
Resource Timing Viewer - Online See All Asset Loads
List all resources loaded by the current page and their detailed timing breakdown. Inâbrowser waterfall.
Mutation Observer Tester - Online DOM Change Watcher
Modify the DOM via buttons and see MutationRecords logged. Understand childList, attributes, and subtree options.
Private State Token Demo - Online AntiâFraud Test
Issue and redeem Private State Tokens (formerly Trust Tokens). Understand how they help detect bots without cookies.
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.
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.
Selection & Range API Demo - Online Get/Set Selection
Select text and see the Selection object properties. Create ranges programmatically. Understand how richâtext editors work.
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.
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.
Constraint Validation API Tester - Online Form Debug
Test required, pattern, minlength etc. See validity states and custom error messages. Learn browserânative validation.
Broadcast Channel API Demo - Online CrossâTab Communication
Open the same page in two tabs and send messages between them. See realâtime crossâtab communication. Learn the API.