In March and April 2017, we have run a voting experiment during the French presidential election. During this experiment, participants were asked to test several alternative voting methods to elect the French president, like scoring methods, instant-runoff voting, Borda with partial rankings. The experiment was both carried out in situ in polling stations during the first round of the presidential election (using paper ballots), and online during the month preceding the first round, and until the second round of the election (using a web application). A total of 6358 participants took part to the in situ experiment and 37739 participants took part to the online experiment. This dataset contains the answers provided by the participants to the online experiment, with no other processsing than a basic transformation to a set of CSV files. The companion paper available on this repository describes the experimental protocol, the format of the files, and summarizes the precise conditions under which this dataset is available.