Caljouw was selected to join the
national team in 2008, and made a debut in international senior tournament in 2012. 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. He was selected by
Badminton Europe to join the Player Development Plan "Future Stars". 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. He defended the title in 2018, after beating Fransman, and also in 2019 beating
Aram Mahmoud in the final and again in 2020 and 2022, each time beating youngster
Joran Kweekel in the final. He reached the semi-finals of the Dutch Open and the Scottish Open both twice in 2017 and 2018. In 2017, he also reached the semi-final of the Bitburger Open in Germany. In 2018 he won his first big title the
Orléans Masters then a BWF Tour 100 event, after defending the title he won the previous year when the event was still an International Challenge event. In 2018, he also reached the final of the US Open, an BWF Tour 300 event. In 2019 he won the Austrian Open and the Kharkiv International, both International Challenge events. == Achievements ==