Applications that process money operate under numerous security constraints and require particular attention. Even small issues, such as an insecure endpoint or an inconsistent workflow, can lead to fraud or financial loss. Yet many Django applications rely on the default setups that are not always suitable for high-risk domains.

In this talk, I will share practical lessons from securing a real-world Django payment system. We will explore how to design reliable transaction flows, enforce data integrity across distributed components, and prevent various attacks. The session covers common blind spots such as race conditions, fraud attacks, unsafe admin usage, as well as the architectural patterns that prevent them.

We will also discuss proper error handling, secrets management, monitoring strategies for abusive behaviour, and how to think like an attacker when evaluating your own code.

Attendees will learn concrete techniques and pragmatic security recommendations to build modern applications that remain secure under high load.