Security is important. Nowadays many malicious third parties are hunting for opportunities to steal personal data or identity and use them for malevolent purposes. We should always protect our data and share it only with the web applications that we know and we trust. To keep the security on a high level and make sure nobody can steal our data, we provide various tools that serve as a security guard. During this talk, I will introduce you to Open Banking, which is the standard way of sharing banking data with Third Party Providers. Then, I will discuss the three security mechanisms that protect Open Banking against malicious parties. I will explain how TLS and mTLS work and what role they play in the Open Banking API. I will show you how Third Party Providers, such as Finanzguru, authenticate themselves before fetching users’ banking data. I will explain how Strong Customer Authentication reduces fraud and helps with user identification. In the end, I’ll show you how Klarna uses AWS services to implement a secure Open Banking API solution.