Modern homes are full of synthetic materials that burn fast and release toxic smoke. So it’s absolutely crucial to own top-notch smoke alarms.Unfortunately, if you’ve equipped your home with suspiciously inexpensive smoke alarms — especially if you bought them online — you might not be able to trust that they’ll work well when you need them the most.It’s not that you can’t find a good smoke alarm online. You certainly can if you know what you’re looking for. But we found more than a dozen smoke alarms, including several best sellers at Amazon and other major internet retailers, that have not earned a basic, industry-standard safety certification required by the vast majority of fire codes across the US.Any smoke alarm you install should be certified to the standards set by UL, the research and testing organization responsible for safety rules governing smoke alarms, among many other product categories.