Instances for the Model Counting Competition 2021 - Track 1 (Model Counting)- Track 2 (Weighted Model Counting)- Track 3 (Projected Model Counting)- Track 4 (Model Counting) The even instances (trackX_000.cnf, trackX_002.cnf, ...) were made public for all participants during the testing phase of the solvers, whereas the private instances (trackX_001.cnf, trackX_003.cnf, ...) were used for the final evaluation and disclosed after the submission. For details, we refer to: https://mccompetition.org/past_iterations. Instances originate from various publicly available data sets and submissions made after a call for benchmarks. The full instances from which we selected is available on Zenodo under - Model Counting Competition 2021: Full Instance Set Details will be made public in the upcoming report. Update v2:Renamed archive for Track 4 (mc2021-track4-pwmc_competition.tar->mc2021-track4-mc2_competition.tar).Track 4 was a model counting track only (no weights, no projection variables).Thanks to R. Bryant for reporting.