The speakers addressed a wide variety of subjects: from "classical" development over marketing to community topics. The main focus this year were topics about agile strategies and tools regarding devops, deployment and development processes. Community related topics gave insights into the (possible) collaboration between open source projects, diversity and the TYPO3 Association.
This is a companion discussion topic for the original entry at https://stage.typo3.org/article/recap-typo3-developer-days-2017/