Ben Nadel opens this course with a familiar story: a team shipping critical bugs to production so often that fixing incidents ate up as much time as building features. Unit tests didn't fix it. Neither did code review, a new tech stack, or simply slowing down releases.
What changed things
The turning point was feature flags — a way to switch code on and off in a running application without a deploy. Nadel frames them as more than a conditional statement: a shift in how a team writes code, coordinates releases, and talks to clients, one that took incidents from a daily occurrence down to a rare exception.
The course builds out from that experience into the practical mechanics of adopting feature flags in your own workflow, aimed at teams who recognize the same release-anxiety cycle and want a way out of it.
Nothing helped reduce the number of downtimes. Unit tests did not solve the problem. Code reviews yielded no results. Changing the technology stack did not help. Slowing down the development cycle didn't work either. Maintaining stable system operation during the evolution of the product became a Sisyphean task.
Until we discovered feature flags. They changed everything. The number of failures and incidents decreased from daily to weekly, and then to rare exceptions.
Feature flags allow you to dynamically enable and disable code in an application while it's running. They can be thought of as a kind of magical conditional operators, but this is only a superficial description. In reality, feature flags are a revolution in the product development process. They change the approach to writing code, team interaction, and communication with clients. Moreover, they create a level of psychological safety that most modern development processes simply do not provide.
When I first learned about feature flags, my reaction was skeptical: “I don't need this.” However, after eight years of working with them, I realized how powerful a tool they are. Today, I cannot imagine product development without feature flags - they have become as much of a basic necessity for me as logs, metrics, and databases.
This book is your guide to the world of feature flags. In it, I will explain what they are, how they work, and how they can transform your entire organization. I will share the experience accumulated over eight years and show how feature flags can create a development culture based on trust, flexibility, and efficiency.
