Kempter, a product of the FC Zürich youth academy, made his league debut for the club on 24 April 2016 in a 3–0 away defeat to Young Boys, coming on as an 81st minute substitute for Vinícius Freitas.
[7] In September 2020, Kempter signed a one-year deal with Swiss Challenge League club Neuchâtel Xamax.
On 27 August 2023, in his fifth start for Grasshoppers he had to be subbed off after a little over 60 minutes with an ACL and meniscus injury, which ended his season prematurely.
[16] Kempter confirmed his decision to represent the Philippines in 2018, but did not receive his first call-up until June 2019 ahead of a friendly against China[17] as the process to secure eligibility documents delayed the switch.
Tang was not booked for the incident, and a disappointed coach Scott Cooper confronted referee Kim Hee-gon at halftime, who allegedly claimed that Kempter "broke his own nose".