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.
UD5 Toolkit
Your browser supports the modern asynchronous Clipboard API.
localhostwriteText in some versionsnavigator.clipboard.read()navigator.clipboard.readText()navigator.clipboard.read()navigator.clipboard) is a modern, asynchronous, promise-based API for reading and writing clipboard data. Unlike the older document.execCommand('copy') method, it supports reading from the clipboard, writing multiple MIME types simultaneously (text, HTML, images), and provides proper permission management. It's more secure, works with Permissions API, and doesn't require creating temporary DOM elements. The old execCommand approach is synchronous, write-only, and being deprecated.
readText() in some configurations, and Safari requires user activation for all clipboard operations. Check the permissions panel above to see your browser's status.
clipboard-write is typically granted automatically in secure contexts without a prompt. clipboard-read usually requires a user gesture (click, tap, or keyboard shortcut) and may show a browser permission prompt, especially for reading non-text formats like images. You can query permission state using navigator.permissions.query({name: 'clipboard-read'}).
navigator.clipboard.write() with a ClipboardItem containing multiple MIME types:const item = new ClipboardItem({'text/plain': new Blob(['Plain'], {type:'text/plain'}), 'text/html': new Blob(['<b>Bold</b>'], {type:'text/html'})}); await navigator.clipboard.write([item]);text/plain, text/html, image/png, image/jpeg, image/gif, image/webp, and text/uri-list (for URLs). Applications can also register custom MIME types for internal use. The Paste Analyzer tab above lets you inspect exactly what MIME types are currently in your clipboard — this is invaluable for debugging rich copy-paste behavior in web apps.
navigator.clipboard.read() to get ClipboardItem objects. Then call item.getType('image/png') to get a Blob, and use URL.createObjectURL(blob) for display or blob.arrayBuffer() for processing. This works for screenshots and copied images. Note that reading images requires the clipboard-read permission and a user gesture in most browsers.
paste event provides access to event.clipboardData which is the data being pasted at that exact moment — it can include additional MIME types added by the source application. The clipboard.read() method reads the current system clipboard. They should generally match, but timing differences or application-specific clipboard formats can cause variations. The Paste Analyzer tab captures the paste event data, giving you a real-time snapshot.
NotAllowedError (permission denied or no user gesture), NotReadableError (clipboard empty or inaccessible), and TypeError (unsupported MIME type). Always check navigator.clipboard exists before calling methods. Provide fallback UI or clear error messages. This tool demonstrates proper error handling in the operation log.
navigator.permissions.query({name:'clipboard-read'}) to check the state. If it's prompt, the next read call will trigger the browser's permission dialog. Once granted, subsequent reads from the same origin may work without re-prompting.
Read, write, and delete cookies using the modern Cookie Store API. Monitor change events. No more document.cookie parsing.
A minimalist text notepad that auto-saves to your browser's localStorage. No ads, no signup, no data leaves your device. Perfect for quick ideas.
Provide a hook name and select features (state, effect, callback). Get a complete React custom hook with TypeScript. Faster development.
Enter a component name and get a basic Vue 3 Single File Component template with script setup. Fast scaffolding.
Apply a tint remover that guesses the original colors from a sepia photo. Not perfect, but fun. All in canvas.
Paste a raw cookie string and see a formatted key‑value table. Debug session cookies and understand flags. Runs in browser.
Scale a classic homemade playdough recipe to any amount. Choose colors with safe options. Simple local calculator.
Store passwords and notes encrypted with a master passphrase. Data lives only in your browser's localStorage. No cloud.
Apply tone mapping algorithms to bring out details in highlights and shadows. Simulate HDR from a single image.
Generate a Next.js page.tsx file with Server Component or Client Component. Layout and metadata included.
Compress and decompress text using the browser's native Compression Streams API. See the binary output size.
Connect a game controller and see every button press, axis movement, and vibration test. Uses the Gamepad API.
Unified input demo: see pressure, tilt, and type from any pointer. Compare pointerType values. Essential for drawing apps.
Modify the DOM via buttons and see MutationRecords logged. Understand childList, attributes, and subtree options.
Drag to resize a box and see the Resize Observer callback fire. Get contentRect and borderBoxSize. Learn the API.
Search and copy HTML entities for arrows, math, currency, and symbols. See the glyph and code. Fast reference.
Decode an image progressively using the ImageDecoder API. See partial results and metadata. Modern alternative to <img>.
Decode individual video frames from a local file using the VideoDecoder API. Step through frames. Cutting‑edge browser feature.
Register a one‑off background sync and see it fire when connectivity returns. Debug service worker sync logic.
Request permission and detect when the user is idle (away from keyboard). See screen lock state. For native‑like apps.
Acquire and release locks across tabs. Prevent race conditions in IndexedDB or localStorage. Visual queue and lock state.
Connect a gamepad and see all button presses and axis movements visually. Check that every input is detected correctly.
Trigger different vibration patterns on mobile devices. Test if your phone supports haptic feedback. Simple demo.
Check notification permission, request it, and send a test notification. Verify icon, body, and tag. Debug web push.
Display your effective connection type (4g, 3g, etc.) and downlink speed using the Navigator API. Adapt your app accordingly.
See your device's battery level, charging status, and discharge time using the Battery Status API. Fun utility.
Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.
Test the new HTML popover attribute for creating accessible tooltips, menus, and dialogs without JavaScript. Copy code snippets.
See the View Transitions API in action. Cross‑fade and morph between two states. Copy the JavaScript starter code.
Test the Web Share API by sharing text, links, and files directly from the browser. Check compatibility and see example code.