Typically, no one is going to release an app or tool without making a buck; thus, there has to be a model for monetization. The main reason to be wary of “free” tech tools: big data. An increasingly common means in which developers profit off their apps is through data collection.
DawsonITE is a blog devoted to Educational Technology. It's compiled by Rafael Scapin, Coordinator of Educational Technology at Dawson College in Montreal (Canada).