Grundmann was The Search Works' top search engine optimisation executive and he leaves less than two months after affiliate firm TradeDoubler took over The Search Works' parent company, The IMW Group, for £56m.
Grundmann has become the first high-profile figure to leave The Search Works following the acquisition. He has spent a decade in the internet industry.
The Search Works has continued to pick up business since the acquisition, most recently the lucrative contract for VisitBritain's global search.