Breaking an API is a pain for many users, so you’d better have good arguments when you decide to do so. In this talk, we'll weigh different arguments against and in favor of API changes. Which arguments are valid and which arguments should be rejected? Should developers go for the short pain when they face a situation where an API change is necessary to solve a problem, or should they postpone the API change by introducing workarounds? How can you avoid that users migrate to another product instead of to the newer version of your own product? Which strategies can be used to introduce a new API? This thought-provoking talk is aimed at developers of SDKs and software libraries. Michaël Demey has been a developer at iText Software since 2011. He has been responsible for customer support and as such, he has a keen insight on how PDF is used in the real world. His personal interests involve Java and other languages that run on the JVM, such as Groovy and Clojure. He's also a contributor to different open source projects. Benoit Lagae is a Java developer by nature who has also branched out towards .NET and Python in recent years. After a higher education in linguistics, he rediscovered his earlier fondness of programming and loves to connect the two as often as possible. He has been a support engineer for iText Software since 2014, focusing on performance, document conversion, fonts, and writing systems. When not at work, he specializes in finding terrible names for his private software projects. [AWL-6219]