Give a stream of consciousness and then the final answer. "In Case You Did n't Know" is a song recorded by American country pop singer Brett Young and co-written by Young, Trent Tomlinson, Tyler Reeve, and Kyle Schlienger. Its official release to radio was on January 9, 2017, as the second single from his debut self-titled EP which had been released on February 12, 2016. The song has been certified 2x Platinum by the RIAA, the first song by Brett Young to receive a Platinum certification.

Based on this passage, who sings. in case you didn't know?
The relevant sentence in the passage is: "In Case You Did n't Know" is a song recorded by American country pop singer Brett Young and co-written by Young, Trent Tomlinson, Tyler Reeve, and Kyle Schlienger.
So, the final answer is American country pop singer Brett Young.