Senior iOS Engineer (Experiments for Conversion Optimisation) in Barcelona or Remote


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Job Description

As Brainly, we aim high πŸ“ˆ. We want to be the best educational app in the world - we are top 1 in 8 countries by now, but that does not mean we can rest on our laurels. We have 350+ million unique users monthly and that number keeps on growing! As such, we are looking for skilled iOS Developers to join our Conversion Optimisation team. The purpose of this team is to de-risk business decisions, learn, and solve customer problems using experiments as our main tool. Becoming the best is then a function of how fast we learn and innovate.

Before you make your decision on helping us in this growth adventure πŸš€, a few significant details:




  • We believe in teamwork, self-organization, and adaptation;
  • We check our hypotheses with A/B tests and let data tell a story not HiPPOs β€” Highest Paid Person’s Opinion;
  • We are free to explore and use new technologies in our projects β€” Break things fast to learn even faster;
  • We deliver fast and often, be ready for a fast-paced environment β€” Currently avg. of 1 app update per week!




  • Swift mixed with some Obj-C code;
  • Firebase;
  • CocoaPods;
  • GraphQL and REST communication with backend;
  • Fastlane and TeamCity for CI/CD automation.




  • Actively designing, developing, and giving inputs to testing variants to validate hypotheses for Brainly mobile platforms to enhance the learning experience for our users;
  • Solving complex challenges such as performance, scalability, and security;
  • Collaborating with other software engineers to design scalable services, plan feature roll-out, and ensure high reliability and performance of your deliverables;
  • Conducting code reviews, contributing high-quality documentation, and building robust test suites for your features.




  • At least 3-4 years of professional experience with Swift and Objective-C;
  • Strong understanding of the iOS SDK;
  • Knowledge regarding Firebase AB testing frameworks (Remote Config, Notifications);
  • Experience with Firebase custom events and mobile analytics;
  • Understanding of how experimentation cycles work, from hypothesis to analysis;
  • Computer science fundamentals - data structures and design patterns;
  • Communication skills to get things done with Data Analysts, UX researchers, Designers and QA Eng. β€” healthy experiments are a team effort and we understand that;
  • Attention to detail from a QA standpoint β€” TBVBP (trust but verify before production);
  • Fluency in English (C1)

You are a top-notch candidate if you also have:

  • Experience crafting testing hypotheses;
  • Experience with monetization testing πŸ’°;
  • Experience in working on projects with large user-base β€” we are at 350M+ monthly users at this point, that is our playground for testing
  • Eagerness to create beautiful, snappy and modern UI


WHAT IS IN IT FOR YOU (On top of the salary that is): 


  • Flexible working hours and the possibility to work remotely
  • Personal development budget 800$ per year + unlimited time off policy for
  • participation in conferences and workshops and access to an online learning platform with courses from Udemy, Harvard Manage Mentor and many others
  • Full medical insurance (including partner and children)
  • Gym & wellness card (including access to gyms, sports classes)
  • Access to the Mental health Helpline - providing virtual support of external psychologists, psychotherapists, and coaches
  • Possibility to join one of our Employee Resource Groups and initiatives (Inclusion Council, Ladies at Brainly, Brainly Cares)
  • If needed, additional budget for remote work accessories


By sending us your application, you agree that Brainly sp. z o.o. with its seats in Krakow, will process your data contained in the form below and in the documents you attach in to participate in recruitment. In connection with this, you have the right to withdraw your consents, the right to access to your data, the right to obtain their copy, rectify them, erase, limit their usage and also data portability right and object to their use by Brainly, as well as to lodge a complaint with the President of the UODO. If you have any questions regarding the use of information about you and exercising your rights related to this use, please contact our DPO - If you want get to know more about how Brainly uses and process your personal data [click here].


About Brainly

  • Ed Tech

  • Krakow, Poland

  • 50-200

  • 2009


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