Runs in your browser
No downloads or sign-ups are required. OpenTally counts are computed entirely inside your browser, and no data ever leaves your computer.
Wide range of STV systems
OpenTally supports Gregory (inclusive and exclusive, weighted and unweighted), Meek and Wright variants of the single transferable vote.
Support for arbitrary constraints
OpenTally is the only publicly available election counting software to support arbitrary combinations of constraints, such as gender quotas and other affirmative action requirements.
Free and open source
Source code for OpenTally is publicly available under the GNU AGPLv3.
From our blog
Latest news and posts from the OpenTally blog
Implementing a BLT parser by hand in Rust (vs pest and combine)
Asyncify with vanilla JS/
WebAssembly (wasm-bindgen compatible)
WebAssembly is a technology for executing compiled programs in the web browser at near-native speeds. However, it has a number of current limitations, including that it does not support coroutines/
In OpenTally, WebAssembly is used to run code for counting an election. This…
Model rules for a single transferable vote election using the weighted inclusive Gregory method
OpenTally is open-source software for counting single transferable vote (STV) elections. The default preset in OpenTally is ‘OpenTally WIGM’, a recommended set of simple STV rules designed for computer counting, using the weighted inclusive Gregory method, exact quotas and rational arithmetic. …