BlaBlaCar: Designing for trust between strangers

People associate hitchhiking with axe murders. So how do you design a service to promote trust between strangers?

Warning: liveblogging

Prone to error, typos and crimes against grammar. Post will be updated and corrected during the talk and over the 24 hours afterwards. 

Nicolas Brusson & Vanina Schick, BlaBlaCar

The story of BlaBlaCar – and how to design for trust between strangers…


It all started in 2006 when they decided to build a new transport network. Even today, we take a train or plane between cities – or even take the bus or drive. The biggest passenger inventory we have is empty seats in cars. In France you have a billion seats travelling empty between cities a year. That’s far more than the capacity of the rail companies. The solution? Build an online marketplace to connect passengers with those empty seats. 

People were sceptical: they thought it “smelt” – weird hitchhikers. How do you overcome that? People also assumed it would be free. For a marketplace to work, you need to transact. But the biggest problem was trust – were they building a supermarket for axe murders? 

The challenge was building trust between people, they realised. They had to rebuild the hitchhiking experience so it was paid, planned and trusted. 


The people we trust are people we’ve met. How do we get people to trust each other when they haven’t met? It’s a wicked problem – one that resists solution, because it’s too intractable. They created a frame work: DREAMS:

  • Declared
  • Rated
  • Engaged
  • Activity
  • Moderated
  • Social

Declared is the first step: name, photo, preferences (are you “bla” – quiet – or “blablabla” – chatty – ?) 

Rated: the two people rate each other – but also use the discussion to send messages to each other

Engaged: You need to know people are committed – so you make them make a financial commitment. 

Activity: Trust doesn’t transfer well across activities. The person who does you ironing isn’t necessarily someone you’d trust to drive you. This service is just about driving. 

Moderation: They are a regulatory body – they create the conditions of trust. They create the rules. They verify the people, and moderate the content on the site.

Social: Our reputations are migrating online. Facebook Connect is used to plug people into their real network. 

Unsurprisingly, strangers were the least trusted category in their research – followed by neighbours and then Facebook Contacts. The research showed that BlaBlaCar profiles created a trust level above colleagues, but below friends and family. 


They didn’t get there in one step – they got there in iterations. In the early days, the site was very basic. No profiles, no ratings. Growth was slow. Online ratings allowed things to take off – but DREAMS allowed serious growth. Last year they did 3m passengers – and this year they think they’ll do 10m.