UD5 Toolkit
CSS Media Query Range Tester – Online Width/Height Debug
Paste media queries and see a visual indicator of which rules apply at current viewport size.
Media Query Live Tester - Online Resize & See Results
CSS Editor — Write your media queries below
📋 Media Query Match Status
No @media rules detected. Add some media queries to see match status.
550 × 520 px
drag to resize
CSS Media Query Tester - Online Verify Breakpoint Conditions
Write a media query and instantly see if it matches your current viewport. Width, height, orientation, and more.
CSS Media Query Generator - Online Quick Syntax Builder
Build a CSS media query by selecting feature, operator, and value. Copy the exact syntax for your stylesheet.
CSS Container Queries Playground - Online Test @container
Experiment with CSS container queries in a live editor. Resize the container and see styles change based on its width/height. Learn modern responsive.
aspect‑ratio with min/max Demo - Online Responsive Boxes
Combine aspect‑ratio with min‑/max‑width/height and see how the box responds. Understand sizing constraints. Copy the pattern.
CSS Media Query Syntax Checker - Online Validator
Paste a media query and instantly check for syntax errors. See if it's correctly formed. Quick developer tool.
Speaker Polarity Test – Online Click & Listen
Generate a pop signal to determine if speakers are wired in phase. Quick stereo test.
Astigmatism Self‑Check Chart – Online Dial & Lines
Display an astigmatism dial and instructions for self-assessment. Educational, not a medical diagnosis.
Spelling Test Practice - Online Audio Dictation & Typing
Hear a word spoken by browser TTS and type the spelling. Choose difficulty or paste your own list. Great for kids. Local only.
Geolocation Override Tester - Online Simulate Any Location
Override your browser's geolocation to any coordinates and test how your app responds. For development and privacy testing.
Speech Utterance Tester - Online Play Word by Word
Hear text spoken word by word with boundary events. See the exact index and character. Advanced TTS dev tool.
Audio/Video Sync Tester - Online Lip Sync Check
Load a video and visually check if audio aligns with lips. Use frame‑by‑frame stepping. Debug playback issues.
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.
PWA Install Prompt Tester - Online Simulate Install
Check if your page triggers the beforeinstallprompt event. Simulate the install flow. Debug PWA installability.
Reaction Time Test - Online Click & Sound
Measure your visual and auditory reaction speed. Average and best times shown. No data collected. Pure Javascript timing.
Accept‑Language Header Visualizer - Online Locale Match
Paste your Accept‑Language header and see which languages your site should serve based on quality values. Internationalization helper.
Network Throttle Simulator - Online Slow 3G & Offline Test
Test how your page loads under slow, 3G, or offline conditions by intercepting fetch and applying delays. No DevTools needed.
Geolocation API Simulator - Online Test Coordinates
Override your browser's geolocation to any coordinates and test how your app responds. For development and privacy testing.
Screen Orientation API Tester - Online Lock & Check
Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.
Fullscreen API Tester - Online Request & Exit Demo
Test the Fullscreen API: request fullscreen on a colored div, detect changes, and copy the JavaScript boilerplate.
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.
Responsive Image CSS - Online Art Direction & Srcset
Upload an image at multiple widths and generate a complete <picture> or <img srcset> snippet. Modern web performance.
Browser Color Gamut Test - Online P3 or sRGB?
Check if your browser and display support the wider DCI‑P3 color space. See the difference with a simple test pattern.
Palindrome Tester - Online Phrase Checker
Enter any phrase and instantly see if it's a palindrome, ignoring spaces and punctuation. Fun for word nerds.
Fake ID Number Generator - Online Test SSN/SIN Lookalike
Generate random, formatted ID numbers that match pattern rules for various countries. For testing input validation. No real data.
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.
Media Device Tester - Online Check Camera, Mic & Speaker
Quickly test if your webcam, microphone, and speakers work correctly. See live video and audio meter. No data sent.
Fuzzy Data Generator - Online Create Random Records
Generate random but realistic‑looking data arrays (users, products, orders) with typos and missing fields. For test robustness.
Eye Dominance Test - Online Find Your Dominant Eye
Simple interactive eye dominance test: hold up a virtual dot and see which eye stays aligned. Educational.
Iframe Sandbox Configurator - Online Test Permissions
Build an iframe with different sandbox flags and see live which features are blocked. For secure embedding.