We are currently looking for a Software Engineer (Python) in Experimentation Squad to join our Platform tribe.
Here in Preply we a/b test most of our changes on production, both product and technical before scaling it to all customers.
Platform tribe owns the whole infrastructure that is used to make those business-vital decisions.

We’re using modern stack, you can check it here: tech-radar.preply.com
We have diverse technical challenges (sometimes we write about them on our Engineering Blog) that will allow you to develop your skills across the stack.

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.

What we are looking for:

• Strong knowledge of Python, at least 2+ 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.

How do we measure success in this role?:

• Review & cover with alerts event tracking pipelines.
• Migrate message bus from Redis to Kafka.
• Implement control group to measure cost of experimentation.
• Rewrite A/B interpretation tool that will unify 3 existing tools.
• Adopt SEO a/b testing framework.

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.

Few more insights on what we do:

Our Engineering Blog: medium.com/preply-engineeringOpen source github.com/...​reply/graphene-federation