Imagine you have to do a simple REST API including 3 endpoints, but in one day, is it ok? Such a small question but with many things into it, it's a cognitive trap, you are evaluating how much you can achieve in a day, your experience with APIs, the tools, the risks and much more things. Your brain has to work a lot to give certain answers, many times without considering all factors. This talk introduces you to the cognitive biases world, exemplified by a developer's life, creating awareness you could be able to avoid many issues in your career!