The International Programme for Development Evaluation Training (IPDET) has moved its 2020 summer school on-line. As an extra, it has opened up its online evaluation hackathon to external people - like me. I have taken up the invitation, registering for my first evaluation hackathon. Our group challenge was to develop a prototype for efficiency measurement. This is what we have come up with: Evaluation United. If you like it, scroll to the bottom of that web page and LIKE it; we're in a competition!