prefers‑reduced‑motion Tester - Online A11y Check
Simulate reduced motion preference and test your animations. Copy the media query snippet. Keep your users safe.
UD5 Toolkit
Float any video on top of other windows — test your browser's PiP support instantly.
Simulate reduced motion preference and test your animations. Copy the media query snippet. Keep your users safe.
Nest elements in 3D space with preserve‑3d vs flat. Rotate the parent and see children behave differently.
Turn your webcam feed into real‑time ASCII art. Adjust density and character set. Fun for streams and demos. No upload.
Load an animated GIF and adjust its frame delay to make it slower or faster. Download the modified GIF. All local.
Apply content‑visibility: auto to off‑screen sections and see the rendering cost drop. Demos for infinite scroll optimization.
Simulate forced‑colors mode and see how your site looks. Adjust CSS system colors. Make your design accessible.
Drag a slider to compare your original image with a compressed version (e.g., WebP). See the quality difference and file size savings.
Simulate adaptive bitrate logic by switching between different quality video segments. See how ABR algorithms work.
Drop an image that might have wrong extension and see its real format (JPEG, PNG, WebP) based on header bytes.
Set start and end times for a video and trim it without re-encoding. Download the clip. Pure browser.
Upload a main image and a folder of tile images, and the tool creates a photomosaic. Rendered in canvas. All local.
Upload an audio clip and generate an animated GIF of its waveform dancing. Shareable sound snippet. Canvas magic.
Animate elements as they enter and exit the viewport using view() timeline. Parallax and reveal effects without JS.
Merge an SRT subtitle file onto a video directly in the browser. Preview and download the resulting video. All local.
Patch the PerformanceObserver and show your page’s Core Web Vitals as you browse. See real‑time scores and suggestions.
Choose tabular‑nums, diagonal‑fractions, ordinal and see the effect on a numeric list. Elegant data presentation.
Paste your Accept‑Language header and see which languages your site should serve based on quality values. Internationalization helper.
Create a simple grid or carousel album with local images and captions. Export as printable PDF. Private.
Use browser compass and geolocation to show which planets and stars are overhead. Minimal, local only.
Compress and decompress text using the browser's native Compression Streams API. See the binary output size.
Test overscroll‑behavior: contain to prevent background scroll or pull‑to‑refresh. See the effect in a live demo.
Check how many pages a PDF has without uploading it (uses FileReader). Also shows file size and title if available. Simple and fast client-side tool.
Reverse any short video clip and download the backward version. Fun for creative effects. Browser‑based.
Convert text and files to Base64 or decode Base64 back to original content. Processed locally with no server upload, ensuring complete data security.
Compress text with Brotli at different quality levels. See size reduction and time. Find the sweet spot for your static assets.
Change how many times an animated GIF loops. Set to infinite or a specific number. Download the modified GIF.
Multiple digital counters for tracking stitches, rows, and pattern repeats. Increment, reset. Works on mobile.
See outerWidth, innerWidth, outerHeight, innerHeight, screenX/Y, and availWidth/Height live. Understand the viewport.
See how a full paragraph looks with your chosen text and background colors. Not just a ratio; the real appearance.
Drop a file to see its MIME type and the first few magic bytes (hex and ASCII). No upload, works instantly.