The Math Olympiad Organization Project is an open-source repository of problems collected from USA Math Olympiad Summer Program handouts (with permissions from their creators), past IMO Shortlists, and past USAMO's, started by Alex Zhu. It differs from other resources in a number of ways:

Alex Zhu is currently maintaining this project, but is looking for someone else to take over. If you are interested in maintaining this project, please contact Alex.

Please report any issues (bugs, confusing features, etc.) with this website at https://github.com/zhukeepa/mathorg/issues.

Many thanks to Evan Chen and Victor Wang for their feedback, Diego Roque for getting the IMO Shortlist and USAMO problems onto the website, and to all the handout authors who contributed their handouts for this project.