Position: Back-End Engineer (Experimentation)
Company: Preply
Category: Python
Experience required: 2y
English level: upper

We are currently looking for a **Back-End Engineer for the Experimentation Squad** with a strong Data background so that you’ll be able to apply the whole spectrum of your skills to maintain and develop the “brain” of the Preply - A/B testing system. 
You can check more about A/B testing in the Preply here: https://youtu.be/XqgX1y2wyEo

Here at 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 the Experimentation Squad, will develop systems that are used by all product and platform squads in their daily work in the decision-making process; figure out how to apply novel experimentation methodologies for the Preply problems; tackle problems that occur in highly loaded systems, such as cross-experiment correlation, data consistency, event deduplication, etc.; design and monitor applications in a way that will guarantee stability and reliability.

This position is the intersection of Data, Development & Research. You’ll use Data skills to write ETLs, and set up alerts on data. Research skills will help to dive deeper into 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 routines and iterate on our A/B system core and A/B visualisation tool.

We work in small teams, thus you will be able to influence system design and contribute a lot to 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.

**As an Back-End Engineer, you will:**
Establish credibility with the quality of the a/b testing system.
Own Data pipelines and ensure Data consistency.
Support & develop a/b testing interpretation tools.
Collaborate with product teams to help them tackle technical issues with a/b testing.
Develop new ways of a/b testing (SEO a/b testing, etc.).
**What we are looking for:**
Strong knowledge of Python, at least 2+ years of experience.
SQL hands-on experience.
Understanding basics of statistical analysis: p-value, null hypothesis, confidence interval - something you should be familiar with (or is ready to learn these concepts and even more)
A passion for analyzing data to inform decisions.
Addiction to measuring and monitoring.
High code-testing standards.
Readiness to take responsibility for systems that directly impact the company's decision-making process.
Willingness to educate colleagues (doing knowledge-sharing sessions).
Passionate about communication.
Minimum B2 English level is a must.
**What we offer:**
An opportunity at a high-growth trajectory company with solid investor backing.
An open, collaborative, and international culture where your opinion is highly valued and appreciated.
Easy-to-reach location, brand new office in Kooperative.
Stock options.
A monthly allowance for self-development on Preply.com.
A competitive financial package, with generous leave allowance and health insurance.