The present study aimed to improve the experiences of pre-service science teachers in content development using Web 2.0 tools and to determine the effects of these experiences on their self-efficacy beliefs in content development via Web 2.0 tools. The present study was conducted with a mixed design that included empirical and phenomenological methods. Forty-two pre-service science teachers participated in the study. During the implementation, pre-service teachers developed content using Web 2.0 tools such as Kahoot, Quizizz, Powtoon, Emaze, MindMeister and Toondoo and shared the content with the class using Edmodo. "Self-Efficacy Belief Scale on Fast Content Development via Web 2.0" was used as pre- and post-tests. Findings demonstrated that pre-service teachers' self-efficacy beliefs and all sub-dimensions of content development via Web 2.0 tools improved as a result of the implementation. The views of them were grouped under seven themes; prejudice, satisfaction, awareness, fun, infrastructure problems, language problems and tool problems. Additionally, when the mean of item responses were examined, it was seen that the highest one was about preparing worksheet self-efficacy belief. Furthermore, it was determined that pre-service teachers were happy to participate in the implementation, recognized ways to integrate technology in their fields, and had fun while developing content.