USPTO or United States Patent a Trademark check search engine allows you to search the USPTO's database of registered trademarks and prior pending applications to find marks that may prevent registration due to a likelihood of confusion refusal.
Used on related products or for related services, and Live. A trademark that meets all three criteria will prevent your trademark from being registered because it creates a likelihood of confusion.
Another example BarkX. This is what appeared. This means it never been trademarked, so you can then used BarkX as a brand.
