Academia is trapped in a collective action problem: open science practices have the potential to benefit the entire research community, but their adoption is limited by incentive structures that fail to reward – and sometimes inadvertently punish – open behaviours at the individual level. Problems of this kind can often be addressed by organising a critical mass of support for new behaviours, prior to their adoption. Despite growing success of such ‘conditional pledge campaigns’ on various online platforms (e.g., Kickstarter, Collaction, Groupon), this approach has yet to take hold in academia. Project Free Our Knowledge aims to rectify this by organising collective action in the research community. Using our platform, researchers can pledge to support open science practices, subject to there being a critical mass of support for the proposed behaviour. If the threshold is achieved, everyone who has pledged is contacted and directed to carry out the action together, thus motivating cultural change with minimal risk to individuals. In this hackathon, we will develop new campaigns using our Github repository (https://github.com/FreeOurKnowledge/website) and post completed campaigns to the FOK website (https://www.freeourknowledge.org).