Speaker Polarity Test – Online Click & Listen
Generate a pop signal to determine if speakers are wired in phase. Quick stereo test.
UD5 Toolkit
Sit at a comfortable distance (about 40–60 cm / 16–24 inches) from the screen. Observe the pattern calmly. If the pattern appears to move, flicker, shimmer, or cause visual distortion — or if you feel eye strain, headache, or nausea — this may indicate visual stress sensitivity. Adjust the spacing (spatial frequency), contrast, and colors to find which combinations trigger or relieve discomfort. Patterns with spatial frequencies of 2–4 cycles per degree of visual angle are most commonly associated with visual stress. This is a screening aid only — not a medical diagnosis.
Generate a pop signal to determine if speakers are wired in phase. Quick stereo test.
Display an astigmatism dial and instructions for self-assessment. Educational, not a medical diagnosis.
Hear a word spoken by browser TTS and type the spelling. Choose difficulty or paste your own list. Great for kids. Local only.
Override your browser's geolocation to any coordinates and test how your app responds. For development and privacy testing.
Hear text spoken word by word with boundary events. See the exact index and character. Advanced TTS dev tool.
Load a video and visually check if audio aligns with lips. Use frame‑by‑frame stepping. Debug playback issues.
Toggle a screen wake lock to prevent the device from dimming or sleeping. See the lock state and learn the API.
Paste your Accept‑Language header and see which languages your site should serve based on quality values. Internationalization helper.
Test how your page loads under slow, 3G, or offline conditions by intercepting fetch and applying delays. No DevTools needed.
Override your browser's geolocation to any coordinates and test how your app responds. For development and privacy testing.
Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.
Test the Fullscreen API: request fullscreen on a colored div, detect changes, and copy the JavaScript boilerplate.
Test the Web Share API by sharing text, links, and files directly from the browser. Check compatibility and see example code.
Check if your browser and display support the wider DCI‑P3 color space. See the difference with a simple test pattern.
Enter any phrase and instantly see if it's a palindrome, ignoring spaces and punctuation. Fun for word nerds.
Generate random, formatted ID numbers that match pattern rules for various countries. For testing input validation. No real data.
Pick a method, URL, headers, and body, then send an HTTP request directly from your browser. Debug APIs easily.
Quickly test if your webcam, microphone, and speakers work correctly. See live video and audio meter. No data sent.
Generate random but realistic‑looking data arrays (users, products, orders) with typos and missing fields. For test robustness.
Create a customizable checkerboard or grid background using pure CSS gradients. Adjust cell size and colors. Copy the code.
Simple interactive eye dominance test: hold up a virtual dot and see which eye stays aligned. Educational.
Build an iframe with different sandbox flags and see live which features are blocked. For secure embedding.
Simulate random mouse moves, clicks, or keystrokes to test idle‑timeout logic. Stops when you move the mouse. Dev test.
Paste a test card number to verify Luhn algorithm, identify issuer (Visa, MC), and check length. No real data.
Play left‑only, right‑only, and frequency sweeps to test your speakers or headphones. Quick audio check.
See a live VU meter of your microphone's input level. Test if your mic is working and adjust gain. Privacy‑friendly.
Create a custom vibration or beep pattern from a short Morse code message. Design unique ringtone ideas.
Convert a photo into a color‑reduced embroidery or cross‑stitch pattern with DMC thread colors. Adjust size and palette. Print chart.
Create a simple tessellation by deforming a square or triangle and repeating it across the canvas. Hypnotic patterns.
Arrange virtual fabric squares or triangles on a grid to preview a quilt pattern. Change colors and sizes. Export layout.