UD5 Toolkit
Cron Expression Tester – See Next 10 Execution Times
Enter a cron expression (e.g., */15 * * * *) and see the next 10 dates and times it will trigger. Also explains the schedule in plain English.
Tag: Tester - API, Regex & More
21+ toolsEmmet Live Tester – Preview Expansions Instantly
Type any Emmet abbreviation and see the expanded HTML or CSS in real time. A playground for learning and perfecting your Emmet skills.
Webhook Tester & Inspector - Online View Incoming Payloads
Generate a temporary webhook URL (mock) and view the JSON payloads sent to it. Great for testing integrations locally.
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.
Unicode Property Regex Tester - Online \p{Script=Greek}
Test regular expressions with Unicode property escapes like \p{Emoji}. See matches live. Modern regex power.
Robots.txt Tester - Online Check URL Allow/Disallow
Enter a URL and a user‑agent to see if it is allowed or blocked by the robots.txt file. Quick bot validation.
SQL JOIN Temperature Tester - Online Quick Join Syntax Checker
Quickly test SQL JOIN syntax (INNER, LEFT, RIGHT, FULL) with a sample database schema. Check logic and see conceptual result set without a real DB. Local only.
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.
Redirect Rule Tester - Online See How Browsers Follow
Enter a URL and see the full redirect chain with status codes and response times. Also validates against your chosen rule.
Local Prompt Tester - Online Simulate LLM Response
Test prompt formatting without calling an LLM. See how your prompt would look with different templates. Dev tool.
Web MIDI Keyboard Tester - Online Visual Note Display
Connect your MIDI keyboard and see pressed notes visually on a piano roll. Check velocity, channel, and aftertouch. No DAW needed.
Gamepad Tester - Online Button & Axis Visualizer
Connect a game controller and see every button press, axis movement, and vibration test. Uses the Gamepad API.
Responsive Breakpoint Tester - Online Drag Viewport Width
Enter a URL and drag a slider to change the viewport width smoothly. See exactly where your layout breaks. No iframe limits.
CSS Container Query Tester - Online @container Playground
Experiment with CSS container queries. Resize a container and see the styles change according to its size, not the viewport. Learn the new spec.
Gradient Previewer - Online Instant CSS Background Viewer
Paste or write a CSS gradient value and instantly see the rendered output. Debug and iterate on gradients quickly. Local preview.
RegEx Tester - Online Regular Expression Builder & Matcher
Build and test regular expressions against sample text. Real-time match highlighting, capture groups display, and flavor options. All inside your browser.
GraphQL Request Tester - Online Simple Client
Enter a GraphQL endpoint, write a query, and see the response. Add headers and variables. Simple testing client.
JavaScript Live Tester - Online Run & Debug Snippets
Write JavaScript code and see the output or console.log results immediately. Safe iframe sandbox. For quick experiments.
Virtual Keyboard Tester - Online Check All Keys Functionality
Press keys on your physical keyboard and see them highlighted on a virtual keyboard. Detects multi-key rollover. Quick hardware check.
Keyboard Layout Tester - Online Visual Key Press Viewer
Press any key and see it light up on a standard QWERTY layout. Check functionality or demonstrate shortcuts.
Gamepad API Tester - Online Visual Controller Check
Connect a gamepad and see all button presses and axis movements visually. Check that every input is detected correctly.