By now, you may have heard that young voters were critical in the election in the United Kingdom earlier this month, helping deliver embarrassing losses to the Conservative Party. As politically active progressives in our 20s, we were eager to help mobilize the youth vote before the election. But we also knew that reaching out to people in our mostly left-wing social bubble would change nothing. Yara’s matches on the dating app Tinder were surprisingly responsive when she suggested that they register to vote. So we decided to scale it up.

With the help of two software engineers, Erika Pheby and Kyle Buttner, we designed a chatbot, a smart computer program that deployed an adaptable script. In the two days ahead of the election earlier this month, the chatbot struck up conversations with thousands of young people between 18 and 25 years old on Tinder. The chatbot talked about politics, with the aim of getting voters to help oust the Conservative government. The results were amazing. Over 30,000 messages reached young people in key constituencies.

This is how it worked: People we recruited from Facebook and Twitter “lent” us their Tinder profiles, and the bot convinced Tinder that their profiles were in geographical locations where the vote was close. In these places, the proportion of 18-25-year-olds was high enough that they could swing the election — if they turned out at the national average. Using the photograph of the person who’d lent their profile, the program would automatically swipe “yes” on every user, and if someone swiped “yes” back, creating a “match,” the bot would ask about the user’s voting plans.If the user planned to vote for Labour (or whatever party best placed to beat the Conservatives), the bot sent a message with a link to the nearest polling station. If the user planned to vote for another progressive party, the bot asked if he or she would consider a tactical vote to beat the Tories, voting for the progressive party most likely to beat the Conservatives in their area. And if the user was voting for a right-wing party or was unsure, the bot sent a list of Labour policies, or a criticism of Tory policies. People who lent their profiles could jump in and chat at any time. And they did.

We were amazed by the number of people saying that they’d spent hours convincing a match 300 miles away that high taxation for the rich would benefit them, because we all benefit from investment in the National Health Service. Others organized dates with people with whom they had compatible politics. The occasional match was disappointed to be talking to a bot instead of a human, but there was very little negative feedback: Tinder is too casual a platform for users to feel hoodwinked by some political conversation. By and large, users surprised us with their receptiveness. Some people who received bot messages asked how they could join us. Our inboxes were flooded. The number of profiles lent to us in just two evenings was incredible — we needed a 10-person team to process sign ups. We knew we were a part of something big.