  Data of long-lived and high profile projects is valuable for research on
successful software engineering in the wild. Having a dataset with different
linked software repositories of such projects, enables deeper diving
investigations. This paper presents 20-MAD, a dataset linking the commit and
issue data of Mozilla and Apache projects. It includes over 20 years of
information about 765 projects, 3.4M commits, 2.3M issues, and 17.3M issue
comments, and its compressed size is over 6 GB. The data contains all the
typical information about source code commits (e.g., lines added and removed,
message and commit time) and issues (status, severity, votes, and summary). The
issue comments have been pre-processed for natural language processing and
sentiment analysis. This includes emoticons and valence and arousal scores.
Linking code repository and issue tracker information, allows studying
individuals in two types of repositories and provide more accurate time zone
information for issue trackers as well. To our knowledge, this the largest
linked dataset in size and in project lifetime that is not based on GitHub.
