ReactionTimeTest is a quick and interactive tool that lets you measure how fast your brain and body respond to a visual signal. With a simple color-change prompt, it challenges you to click as soon as you see the screen shift—typically from red to green. Your response time is recorded in milliseconds, giving you instant feedback on your reflex speed. Whether you're testing your focus, warming up for esports, or just having fun, ReactionTimeTest offers a fast, free, and easy way to engage your mind. No login or app download is required, and it works seamlessly on both desktop and mobile browsers. Repeat the test as many times as you like to improve your results or compare scores with friends. Great for casual users, athletes, and even cognitive research, ReactionTimeTest turns a simple activity into an insightful look at your reaction ability.