Nginx is developed by a commercial company having very highly qualified full-time paid software engineers. At the same time, the open source version of Nginx, which covers 99% of your needs, is always available both as a collection of versioned tarballs and as a Mercurial repository with commits history under a very permissive BSD license that allows modification and redistribution. This is a unique opportunity to learn from a corpus of very effective and professional C code. Nginx supports modules, and there are numerous third-party Nginx modules available (see the official wiki page https://www.nginx.com/resources/wiki/modules/). Nginx module development is the main way to customize the software for specific needs and is a very valuable skill that you may build your career on.

Nginx is written in C language with very little external dependencies. It contains its own highly effective library of primitive data structures and algorithms, such as hash tables, radix trees, and very efficient self-balancing red-black trees. Reading some clean-and-lean code is a special pleasure, and Nginx fully delivers on that front.

There are success stories about using customized Nginx as a web application platform, and for a great example, see the earlier-mentioned OpenResty. Although we cannot recommend this approach to businesses yet, being a developer in a company that has chosen Nginx as a platform may be a great way to become a rare specialist, who are always in high demand.

The most important benefit that you get from the open nature of Nginx combined with software engineering skills is an ultimate troubleshooting method: source-level debugging from inside Nginx. Nginx has great logging facilities, but nothing compares to the ability to step through critical sections in a debugger or modify the source to trigger rare conditions. And this brings us back to the main topic of this book. No matter how stable and robust Nginx has become over the years, it is still a piece of software that is written by humans and that is run in faulty, unpredictable, and mind-bogglingly complex environments. We hope that this book provided you with some new tools in your noble quest to run the fastest and the most valuable websites you can imagine.