Fuelled by increased interest among organizations to team up with their customers, technologies for supporting open innovation are emerging. In this paper, we explore how current technologies are designed to support open innovation, in order to envision future developments and research challenges. A sample of 51 systems has been classified. Surprisingly, we found that most technologies for open innovation are not very innovative because they provide similar features. Typically, users are asked to suggest ideas or solve predefined problems in collaboration with others. By drawing on our review, we identified four types of open innovation systems: idea management system, problem solving system, marketplace system and innovation analysis system. In conclusion, we noted that a key challenge for research and practice is to gain a deeper understanding of how collaboration technologies can be connected with more sophisticated opportunities for reflection and analysis.