Droop is a Python-based framework for implementing single transferable vote (STV) counting rules. It allows rules to be implemented in such a way that the the logic is self-contained and can be seen to implement the rule's legislative or other formal requirements.

Droop includes support for fixed-point, guarded fixed-point (quasi-exact) and rational arithmetic. It currently supports variations on Meek, Warren and WIGM rules, including PR Foundation reference rules, as well as Scotland's and Minneapolis MN's WIGM variants.

Droop is a project of the Proportional Representation Foundation.