Open-source election counting
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OpenTally is an application for counting various preferential voting elections, with an academic focus, and emphasis on configurability.

OpenTally may be used in a number of different ways:

  • as an online web application, no installation or special software required
  • as a standalone command line application
  • as a Rust library within another application


OpenTally accepts data in the BLT file format, and can count votes using:

OpenTally is highly customisable, including options for:

  • different quotas and quota rules (e.g. exact Droop, Hare)
  • calculations using fixed-point arithmetic, guarded fixed-point (quasi-exact) or exact rational numbers
  • different tie breaking rules (backwards, random, manual) with auditable deterministic random number generation
  • multiple constraints (e.g. affirmative action rules)
  • equal rankings

Online usage

See the quick start guide for how to use OpenTally online.

Command line usage

OpenTally may also be invoked as a command line application. Run ./opentally --help to view help.

For example, run ./opentally stv path/to/blt_file.blt --ties backwards random --random-seed foobar.