CODECHECK is an initiative in which independent, volunteer “codecheckers” run the code underlying scientific articles and confirm that the calculations and results are indeed reproducible. Researchers can obtain an official Certificate of Executable Computation, with its own DOI, for their published analyses. A certificate can be obtained in several ways, for example through journals and conferences that have already integrated CODECHECK, or via the “Buddy Exchange” programme based on the principle “give one, get one”: those who check someone else’s code will in return have their own code certified.