By SABC Sport
2nd January 2023
The 26-year-old will spend the second half of the current season at the 2. Bundesliga club, where he hopes to play more regularly.
Rapp has been struggling to find game time at Werder and has so far played only 67 minutes for the club.
Now the midfielder is expected to be given many more opportunities, while Werder remain optimistic that he can become a Bundesliga player for them in the future.
"'Rappo' approached us because he wants more playing time than he has been given recently," said Werder Bremen head of scouting and professional football Clemens Fritz.
"With the loan to Kaiserslautern, we want to make this possible for him, but we also still see the potential in him to make more appearances in the Bundesliga."