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Swap My Vote

Swap My Vote is a platform which allows voters to find a partner to swap their vote with. Rather than voting for their preferred minority party in a constituency where a tactical vote is necessary or worthwhile, a voter can find someone who will vote for their preferred party somewhere where that vote makes sense, even under the First Past The Post voting system. In return, they will vote for their partners preferred party as a tactical vote in their own constituency.

Swap My Vote ran a successful project in both the 2015, 2017 and 2019 UK general elections at, and is preparing to do the same for the 2024 general election too.

In the interests of transparency, all of the code that we have written and used is available in this repository. We are in the process of working out how to make this project sustainable, but providing an open and welcoming community for continued developed will be important. So please have a look at the Contributing and Contact sections below if you'd like to help.

Setting up Swap My Vote locally

You will need Ruby and Yarn installed.

  • Clone this repository:

    git clone
  • Install the necessary gems:

    bundle install

    If this fails with error messages that mention pg or PostgreSQL, then try instead:

    bundle install --without=production

    since the PostgreSQL database is not normally needed for local development (sqlite is used instead).

  • Install npm packages with Yarn:

    yarn install

    If you get an error similar to "The engine "node" is incompatible with this module" then you may need to update to a more recent version of node.js.

  • Set up some credentials and other config variables in a .env.development.local file. You can ask @aspiers for a copy of this file, or if you are using your own Facebook and Twitter apps for login then you can make it yourself by starting from a template:

    $ cp .env.example .env.development.local

    Now edit .env.development.local to contain the appropriate credentials. These will get automatically loaded via the dotenv-rails gem.

  • Set up the database schema and populate it with constituency and poll data, as well as some test users accounts for local development.

    bundle exec rake db:setup
  • environment variables

    You will need to be aware of two environment variables.

    • ELECTION_DATE needs to be set permanently to the date of the election in format YYYY-MM-DD. This has an impact on your local site
    • ELECTION_TYPE should preferably be set permanently to 'general' or 'g'. It's possible to omit this step, but the database will be queried more often if it is not set. It may also need to be set for rake db:seed to run correctly for a by-election.
  • Seed the database

    Put some default content into your database

    ELECTION_TYPE=(g or b) bundle exec rake db:seed
  • Run the application:

    # Ensure binding to localhost even if $HOST is set, so that
    # the URL is accepted by the facebook development app
    ELECTION_DATE=YY-MM-DD bundle exec rails server -b localhost
  • Open your browser to http://localhost:3000.

  • Run Guard during development to automatically run tests and do style linting:

    bundle exec guard
  • [rspec-snapshot]( is used for some of the tests. To update the snapshots, do:

    UPDATE_SNAPSHOTS=true bundle exec rspec

    or just for a subset of the tests:

    UPDATE_SNAPSHOTS=true bundle exec rspec spec/foo/bar
  • Database migrations

    When you pull from swapmyvotemaster and database migrations (files in db/migrations) are included you'll need to run

    bundle exec rake db:migrate

    And for tests to keep running successful you'll also need to run

    bundle exec RAILS_ENV=test rake db:migrate

    The test database should be empty, do not run the seeds task against it, some tests will fail.

Note that in the development environment, emails are not sent but instead written as files in the tmp/mails/ subdirectory.

Contributing to Swap my Vote

Any help would be well appreciated!


Before we can accept contributions from you, please make sure you read the License section below and follow the required step.

Deciding what to work on

Please take a look at the GitHub project. Issues are sorted into milestones, and the items are roughly sorted by priority descending, so a good place to start would be near the top. If you can, please avoid tackling stuff in future milestones until the current milestone is complete.

In addition, look out for issues labelled help wanted or easy.

Coordinating with the team

If an issue is already assigned, then probably someone is already working on it or at least intending to. If it's unassigned then probably it's up for grabs. However it's safer to ask in the issue and/or in the Zulip #general chat channel before starting on anything, to avoid accidentally duplicating effort. Please email us at the below address to request an invite to our Zulip chat server.

Our roadmap can be seen in our list of milestones.

Submitting issues and pull requests

When submitting new issues or PRs, please remember to apply any relevant labels. Thanks!


Our docs are currently very thin on the ground, but you will find a few things in the doc/ directory, in particular the admin guide which contains a cheatsheet for administering a live site.


You can contact us at


In order to help ensure that potential voter partners aren't split across different otherwise identical vote swapping platforms in the same country, we have decided to license the code for the time being as follows:

All Rights Reserved © Forward Democracy Limited.

Issue #33 includes previous discussion which may clarify the motivation for this decision.

Contributions to the code will be very gratefully received! Please first use this link to submit a pull request which adds your GitHub username to the .clabot file. It will auto-populate the commit message with a statement that you agree to assign rights for your contributions to Forward Democracy.

Once we merge this pull request, your GitHub username will be added to our list of approved contributors, and any other pull requests from you can then be accepted. This puts us in a future-proof position regarding copyright, e.g. it keeps the possibility to making some or all of the codebase Open Source in the future.