From 2012 on he assumed responsibility for the further development of the extension wt_spamshield. In 2015, the team of TRITUM decided to take over the development of the TYPO3 system extension "form". Ralf is the one who did all the coding and rewrote EXT:form.
This is a companion discussion topic for the original entry at https://typo3.org/article/say-hello-to-our-new-core-team-members/