UD5 Toolkit
Robots.txt Generator - Online Create & Validate Robots File
Build a properly formatted robots.txt file with user-agent rules and sitemap location. Validate syntax in real time. Essential for webmasters.
Random User Agent String Generator - Online for Testing
Random User Agent Generator
Generate realistic user agent strings for browser testing, web scraping, and device emulation.
Choose your OS, browser, and device type – or let the tool surprise you. Perfect for QA engineers, developers, and privacy testers.
No user agent matches the selected filters. Try different options.
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Frequently Asked Questions
A user agent (UA) string is a text identifier sent by your browser to websites. It tells the server what browser, operating system, and device you are using, helping sites deliver the right content and layout.
Random UA strings are essential for testing responsive designs, web scraping (to avoid blocking), privacy testing, and verifying that analytics correctly track different devices and browsers.
Yes! The tool draws from a curated pool of modern, real-world UA strings covering popular browsers and operating systems. They reflect actual traffic you'd see in the wild.
Absolutely. Rotating user agents helps avoid rate limiting and detection when scraping responsibly. Combine with other headers and respect robots.txt.
Browser vendors release updates frequently. We keep our pool current with recent Chrome, Firefox, Safari, and Edge versions. For the latest testing, you can always generate fresh ones.
Spoofing means changing your browser's UA string to mimic another device or browser. It's used for testing, privacy, or accessing mobile-only content. This tool helps you create spoofed strings easily.
Yes, 100% free with no registration. Generate as many random user agents as you need for your development and testing workflows.
User Agent Parser - Online Browser & OS Detector
Paste a user agent string to get a human-readable breakdown of browser, operating system, and device. See your own current agent info automatically.
Random Sentence from Corpus - Online Paste & Generate
Paste your own text and generate a random sentence that mimics its style. Use for creative writing prompts or testing. Fully local.
Robots.txt Validator & Parser - Online Check Syntax
Paste robots.txt content and parse it to check validity, find disallowed paths. Educational SEO tool. Local processing.
Secret Santa Generator - Online Pair Randomizer with Exclusions
Assign Secret Santa pairings from a list of names with spouse/partner exclusions. Optionally email results via mailto link. Fully local, no server.
Coin Toss Probability Demonstrator – Online Long‑Run Simulator
Virtual flip coins thousands of times and see the heads/tails ratio converge to 50%. Interactive law of large numbers.
Push Notification Tester - Online Generate & Receive
Register a service worker, subscribe to push, and send a test notification using a VAPID key pair. Step‑by‑step demo.
Robots.txt Validator - Online Check Syntax & Rules
Paste a robots.txt file and validate its syntax. See if a specific user‑agent can access a path. Essential for webmasters.
Random Encouragement Generator - Online Cheer Up Words
Click for a warm, encouraging sentence to lift your spirits or support a friend. Small positive boost. No repeats.
Random Yes No Decision Wheel - Online Spinner with Sound
Spin a colorful wheel that lands on Yes, No, or custom answers. Includes sound effects and adjustable probability. Local fun decision maker.
Random Quarterly OKR - Online Corporate Fun
Create a random, aspirational quarterly objective with unrealistic key results. For meeting icebreakers.
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.
Speech Recognition Tester - Online Web Speech API Demo
Test your browser's built‑in speech recognition. Speak and see the transcribed text appear live. Must‑have for voice app devs.
CUID Generator - Online Collision‑Resistant IDs for Frontend
Generate CUIDs that are optimized for horizontal scaling and collision resistance. Great for client‑side IDs. Pure JavaScript.
Regex Catastrophic Backtracking Tester - Online Benchmark
Test a regex against long strings and measure execution time. Detect catastrophic backtracking patterns. Visual warning if slow.
WebGPU Compute Benchmark - Online GPU Performance Test
Measure your browser's GPU compute power using a simple WebGPU matrix multiplication. See raw FLOPS and compare with peers. Fully client‑side.
Speech Dispatcher Tester - Online Explore All Voices
List all available TTS voices on your system. Test each with any text. Adjust rate and pitch. Find the best voice.
Simple Invoice Generator - Online Create & Print Invoices Free
Fill in your details and generate a professional-looking invoice ready to print or save as PDF. No sign-up, all data stays on your device. Great for freelancers.
CSS Opacity & RGBA Generator - Online Transparency Tool
Adjust opacity visually with a slider and see the different CSS representations (opacity property vs RGBA/HSLA). Copy best option.
Responsive Iframe Generator - Online Embed Snippet
Enter a URL and generate a responsive iframe embed code with correct aspect ratio. Supports YouTube, maps, and more.
Simple Invoice Generator - Online Create & Print Invoices Free
Fill in your details and generate a professional‑looking invoice ready to print or save as PDF. No sign‑up, all data stays on your device.
Responsive Design Emulator - Online Test All Device Sizes
See your website inside iframes at multiple breakpoints simultaneously. Side‑by‑side responsive testing.
Lit Element Skeleton Generator - Online Quick Starter
Generate a Lit Element web component skeleton with styles and properties. Copy and start coding immediately.
Meeting Invite ICS Generator - Online Apple/Outlook Event
Fill in title, date, time, and location to generate a downloadable .ics meeting invitation. Works with all major calendars.
Virtual Flashlight - Online Color & Strobe Screen
Turn your browser screen into a full‑color flashlight or strobe. Adjust brightness and color. Simple utility.
Random Animal Soundboard - Online Hear Real Calls
Click buttons to play real animal sounds: lion roar, bird tweet, dolphin click. Studio recorded. No load.
REM to PX Converter - Online Root EM Unit Calculator
Convert REM values to pixels and vice versa based on your root font size. Essential for scalable web typography.
CSS Box Reflect Generator - Online WebKit Mirror Effect
Create a reflection effect for images or text using box‑reflect. Adjust direction and offset. Copy the CSS.
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.
PX to EM/REM Converter - Online Responsive Unit Calculator
Convert pixel values to em and rem units based on a base font size. Bidirectional. Must‑have for front‑end developers.