WebSocket Load Tester - Online Simulate Many Clients
Open many parallel WebSocket connections and send messages. Test your server's concurrency. All from your browser.
UD5 Toolkit
Open many parallel WebSocket connections and send messages. Test your server's concurrency. All from your browser.
Test prompt formatting without calling an LLM. See how your prompt would look with different templates. Dev tool.
Generate a temporary webhook URL (mock) and view the JSON payloads sent to it. Great for testing integrations locally.
Run the classic FizzBuzz with custom rules. See the output for any range. A beginner programmer's playground.
Adjust letter‑spacing and word‑spacing with a slider and see the effect on a sample paragraph. Copy the CSS.
Experiment with the Federated Credential Management API. Simulate a sign‑in flow without third‑party cookies. Privacy‑first.
Upload an image and add inspirational or sarcastic title and text. Create classic poster‑style memes. Download as PNG.
Set a cron expression and see a calendar of the next 1,000 execution times. Never miss a schedule again.
Create a Review or aggregateRating structured data. Perfect for star ratings in search results. Copy the code.
Enter a GraphQL endpoint, write a query, and see the response. Add headers and variables. Simple testing client.
Generate a plausible technical blog post title. Useful for practice writing or placeholder content. All local.
Generate random icebreaker questions for meetings, parties, or classrooms. Categories for work, fun, and deep talks.
Acquire and release locks across tabs. Prevent race conditions in IndexedDB or localStorage. Visual queue and lock state.
Generate a random emoji for reactions, game prompts, or just fun. Full Unicode emoji set. One-click copy.
Drag a battery, resistor, LED onto a grid and simulate current flow. Show Ohm's law in action.
Paste a passage and automatically remove every nth word to create a fill‑in‑the‑blank exercise. For teaching and self‑study.
Create a futuristic robotics or AI startup name with an available .com domain check simulation. For brainstorming.
Use your microphone to detect the dominant frequency of ambient sounds. Visualize the spectrum. Local Web Audio.
Click to get a randomly generated, unique favicon. Download as .ico or SVG. For when you need a quick icon.
Generate random JSON data with customizable fields (users, products, orders). Useful for frontend mocking. All local.
Calculate large Fibonacci numbers in a Web Worker. See the UI remain responsive. Copy the pattern for your app.
Build a complex mailto: link with to, cc, bcc, subject, and body. Get the HTML anchor tag. Local.
Simulate paint colors on a pre-loaded room photo by adjusting hue, saturation. Find your perfect shade before buying. Local canvas.
Pop the virtual bubble wrap with mouse or touch. Satisfying sound and reset button. Pure stress‑busting fun in your browser.
Adjust an audio file's volume to a target loudness level (e.g., -14 LUFS). Prevent clipping. Works in the browser.
Build cron expressions using a visual editor with dropdowns. See human-readable description and next run times. Easier than raw cron.
Assign an ICC profile to an image and simulate how it would look on another device. For accurate color workflows. Local.
Decode the header and payload of a JSON Web Token (JWT) without verifying the signature. Inspect claims securely on the client side. Great for developers.
Enter keywords and get domain name ideas by mixing, prefixing, suffixing, and replacing. Check availability indication.
Enter an emoji or any Unicode, and get the valid Punycode for use in a domain name. Geeky and fun.