Björn Ólafur Jóhannsson

Software Engineer at QuizUp. Before i joined QuizUp i was a student at Reykjavik University. I've worked on mobile and server codebases as well as scaling and optimizing QuizUp's infrastructure.
2014-05-21 - 2016-08-31
Server engineer
QuizUp is a mobile trivia game, which reached over 80 million users across the world, peaking at 1.2M daily active users.
  • I wrote the initial implementation of an A/B testing service which allowed QuizUp to run feature experiments. As a side-effect this service alleviated the stress of shipping the mobile clients by making it possible to slowly roll out features and rolling back if we discovered bugs without submitting another binary version.
  • Storage optimisation: Optimized how QuizUp stores information on questions players have seen (essential for picking questions). This optimization reduced a 7TB dataset to 300GB without loosing precision or functionality.
  • Player search: Built a service for search using ElasticSearch that searches for players most relevant to you, using friends, mutual friends, and ranks strangers that have mutual interests with you as more relevant.
  • On-call: I was part of a weekly on-call rotation at QuizUp. If anything critical happened to our systems off-hours, the on-call person will respond and fix if possible, otherwise call the service owner and follow through with fixes and post-mortems.
  • Game service: Worked on refactoring and rewriting the game flow in the backend system of QuizUp, with the goal of handling the scale of 2M concurrent users.
Reykjavik University
Computer Science - BSc.
2012-07-20 - Uncompleted
Native speaker
Programming languages
  • Scala
  • Java
  • Python
  • Android
  • Javascript
  • Amazon Web Services (AWS)
  • High throughput and low latency systems
  • Docker
  • Pants (build system)
  • REST
  • Thrift
    System administration
      • ElasticSearch
      • DynamoDB
      • Redis
      • Memcached
      • PostgreSQL
      Competitive Gaming
      • Rocket League
      • Counter Strike
      • World of Warcraft
      • League of Legends
      • Golf
      • Basketball
      • Frisbee golf
      • Soccer

      CTO - QuizUp | [email protected] | tel: (354) 662-4766
      Jóhann Þ. Bergþórsson
      VP of engineering - QuizUp | [email protected] | tel: (354) 664-0010
      Árni Hermann Reynisson
      Server Discipline Lead - Quizup | [email protected] | tel: (354) 863-7208
      Gunnar Kristjánsson