I've been looking for an appropriate dead pixel tester that runs in a browser, rather than a desktop app. I couldn't find one, so I made my own.
Pixel defects (commonly referred to as dead pixels) are an unfortunate reality of the manufacturing process. Today, most manufacturers have systems in place to catch and correct these errors, but sometimes a defective pixel will slip through. This is one of the main reasons that manufacturers offer warranties on their televisions.
Dead pixels are generally transparent or black in color and may be either stuck on or off (like a light switch). Depending on where they are located on the screen, they may appear as dots or lines. Dead pixels can be caused by many things, including dust particles or improper chemical bonding during manufacture. They can also be caused by electrical stress during shipping or excessive temperature changes.
If you find a dead pixel on your new TV or display screen of mobile or personal computer, the first thing you should do is check out the warranty information that came with it. If you bought your TV within the past two years (and depending on the manufacturer), there is likely a warranty that covers this problem for free repair/replacement, and before all of this check for dead pixel on this dead pixel test
TIP: If you're more than two years out from your purchase date and need to replace your TV because of dead pixels, contact customer service and see what they can do for you!