We are currently looking for a Back-end Engineer in the Experimentation Squad with a strong Data background, so that you’ll be able to apply the whole spector of your skills to maintain and develop the “brain” of Preply — A/B testing system.

Here in Preply we a/b test most of our changes on production, both product and technical before scaling it to all customers. Experimentation Squad owns the whole infrastructure that is used to make those business-vital decisions.
You, as a part of Experimentation Squad, will develop systems that are used by all product and platform squads in their daily work in the decision making process; tackle problems that occur in highly loaded systems, such as cross-experiment correlation, data consistency, event deduplication, etc.; design and monitor architecture in a way that will guarantee stability and reliability in the highly variative environment where 60+ developers deploy production 50+ times a day.

This position is in the intersection of Data, Development & Research. You’ll use Data skills to write ETLs, setting up alerts on data. Research skills will help to dive deeper in the data and experiments, to identify what is going wrong, how to fix it and how to prevent it from happening again in the future. Finally, you’ll use Dev skills to automate routine, iterate on our A/B system core and A/B visualization tool.

You, as a part of Experimentation Squad, will:

• Develop systems that are used by all product and platform squads in their daily work in the decision making process: a/b testing visualisation, a/b testing alerting, data validation, tracking pipelines (Kafka, S3, Redshift).
• Tackle problems that occur in highly loaded systems, such as cross-experiment correlation, data consistency, event deduplication, etc.;
• Design and monitor architecture in a way that will guarantee stability and reliability in the highly variative environment where 60+ developers deploy production 50+ times a day.

We work in small teams, thus you will be able to influence system design and contribute a lot in the company’s growth, also we promote self-direction to work on meaningful projects, while we also strive to create an environment that provides the support and mentorship needed to learn and grow.

We’re using modern stack, you can check it here: tech-radar.preply.com
Our Engineering Blog: medium.com/preply-engineering
Open source github.com/...​reply/graphene-federation

What we are looking for:

• Strong knowledge of Python, at least 3+ years experience.
• SQL hands-on experience.
• Understanding basics of statistical analysis: p-value, null hypothesis, confidence interval — something you should be familiar with.
• A passion for analyzing data to inform decisions.
• Addiction to measuring and monitoring.
• High code-testing standards.
• Readiness to take responsibility of systems that directly impact company decision making process.
• Minimum B2 English level is a must.

Responsibilities:

• Establish credibility with the quality of the a/b testing system.
• Develop new ways of a/b testing (SEO a/b testing, etc.).
• Own Data pipelines and ensure Data consistency.
• Support & develop a/b testing interpretation tools.
• Integrate with 3rd party providers.
• Collaborate with product teams to help them tackle technical issues with a/b testing.

Learning opportunities in this role:

• Boost skills in statistical analysis of A/B testing on practice in company where we run more than 150 A/B tests simultaneously.
• Work together with DA from Booking.com.
• Be in the middle of Development, Data Analytics, SEO & Marketing will help to build T(M)-shaped skills.
• Build, Maintain and Monitor tracking pipelines with high volumes of data.

What we offer:

• An opportunity for personal and professional growth, supported by high functioning teams, stellar investors and the exciting challenges that come with joining a company at the start of its growth trajectory.
• Easy-to-reach location, brand new office in Kooperative.
• An environment free of bureaucracy and corporate constraints; a culture where your opinion is highly valued and appreciated.
• An open, collaborative, dynamic and international culture.
• A monthly allowance for self-development on Preply.com.
• A competitive financial package, with generous leave allowance and health insurance.