The Twelve-Factor App methodology is a methodology for building software-as-a-service applications. These best practices are designed to enable applications to be built with portability and resilience when deployed to the web.
The methodology was drafted by developers at Heroku, a platform-as-a-service company, and was first presented by Adam Wiggins circa 2011.
An Nginx architect argued that the relevance of the Twelve-Factor app concept is somewhat specific to Heroku, while introducing their own (Nginx's) proposed architecture for microservices. The twelve factors are however cited as a baseline from which to adapt or extend.