Stef Caers (Dutch pronunciation: [stɛf ˈkaːrs]; born 5 July 1980), known professionally as Gustaph (stylised as GVSTΛPH), is a Belgian singer-songwriter, producer and vocal coach.

[4] He started his musical career while studying at the Royal Conservatory of Ghent, initially using the stage name Steffen.

[8] In addition to his career as a singer, he works as a vocal coach, and as a teacher at the Royal Academy of Fine Arts (KASK) in Ghent.

[8] In November 2022, Caers was announced as one of seven participants in Eurosong 2023, the Belgian national selection for the Eurovision Song Contest.

[9] His entry "Because of You" won the final on 14 January 2023 and represented Belgium in the Eurovision Song Contest 2023 in Liverpool, United Kingdom, finishing 7th place.