Can my prospective employer check my social media?

To a limited extent, yes. BDSG Section 26 regulates data processing in the employment context: employers may view publicly accessible professional profiles (LinkedIn, Xing, public GitHub repos). Private profiles (Facebook, Instagram) may not be infiltrated through friend requests. GDPR: any data collection about applicants must be proportionate and serve a legitimate purpose. Anti-Discrimination Office: if social media research reveals discriminatory characteristics (AGG Section 1) and leads to a rejection — that is problematic. Practical recommendation: Google yourself and make sure nothing compromising is publicly visible. Actively maintain and optimise professional profiles.