Caljouw was selected to join the national team in 2008, and made a debut in international senior tournament in 2012.

[2][3] Caljouw competed at the 2013 European Junior Championships in Ankara, Turkey, winning a silver medal in the boys' singles event, and also a bronze medal in the mixed team event.

[4] He was selected by Badminton Europe to join the Player Development Plan "Future Stars".

[5] Caljouw won the men's singles National Championships title in 2017, beating defending champion Erik Meijs in the semi-finals and first seeded Nick Fransman in the final.

Boys' singles The BWF World Tour, which was announced on 19 March 2017 and implemented in 2018,[7] is a series of elite badminton tournaments sanctioned by the Badminton World Federation (BWF).