Jones Ralfy Jansen (born 28 April 1992) is an Indonesian-born German badminton player who currently represents Germany.

[3] He won his first senior international title at the 2013 Portugal International tournament in the mixed doubles event partnered with Keshya Nurvita Hanadia.

[4] He also won the 2014 Finnish and Turkey International tournaments with his sister Cisita Joity Jansen.

[5][6] His father Joy Jansen is German, while his mother Meity Rumayar is Indonesian.

He was born and raised in Indonesia with his elder sister Cisita Joity Jansen who is also a badminton player.