Sergey Vasilyev

  • Email: (preferred).
  • Phone: +49 157 3232 0684.
  • Location: Berlin, Germany.
  • Work permit: NE (Niederlassungserlaubnis, Germany).


A skilled developer with ~20 years of experience. Master of Computer Sciences majored in Distributed Computer Systems. Author of Kopf, a Kubernetes OPerators (Pythonic) Framework: Talks:

Keywords: Python, Pytest, MySQL, Postgres, DevOps, Kubernetes, Docker, AWS, SaaS, PaaS, IaaS, Cloud, etc.


Software Engineer
Datafold, Inc.

Data reliability platform; a seed-stage/series-A startup with ≈20+ employees.
Oct 2021–now. Worldwide-remote (from Berlin, Germany).

Develop and maintain the whole spectre of the backend services in the app: from the API (FastAPI) to background jobs covering such subsystems as time series of custom metrics, simplistic anomaly detection and alerting, data diffing and profiling, column-level lineage graph, GitHub/GitLab/Slack integrations, enterprise authentication (SSO, SAML, oAuth2, etc), so on — everything necessary for customer satisfaction and ensuring the reliability of the customers’ data. Python, FastAPI, Celery, Postgres, ClickHouse, Neo4j.

Senior Backend Engineer in Pricing & Forecasting
Zalando SE

One of the biggest European e-commerces and a fashion platform; ~15000 employees.
Feb 2018 – Sep 2021. Berlin, Germany.

Maintained & refactored a Machine Learning platform for article sales & demand forecasting. Migrated the data processing and sales forecasting pipelines from raw AWS+STUPS to Kubernetes, and solved the data gravity problem.

Mentoring junior and middle Software Engineers and advising the Data Scientists on best software development practices, CI/CD workflows, software architectures, tips and tricks.

Senior Python Developer / TeamLead Integration
ProfitBricks GmbH (renamed to Ionos SE)

Could computing IaaS company; 100+ employees.
Sep 2015 – Jan 2018. Berlin, Germany.

Developed an ecosystem (frameworks, toolkits, CLIs/UIs, infrastructure, guidelines, documentation, etc) for integration- & performance- & endurance- & stress-testing of a cloud (IaaS). Led a team of 3 Python developers, plus a group of QA engineers.

Senior Software Engineer in QA Infrastructure

International backup solution provider; 700+ employees.
Nov 2014 – Aug 2015. Moscow, Russia.

Maintaining and improving the infrastructure and the tools for the QA automation team.


Real estate web portal and aggregator; 80 employees.
July 2012 – February 2014 (1 year 8 months). Moscow, Russia.

The same as for the Head of Development below, plus the IT department.

With the IT team:

Reworked the whole infrastructure, and virtualized everything with no harm to the system. Moved most of the infrastructure from ancient collocated bare-metal servers to rented modern servers (including the refactoring of the infrastructure so that it becomes possible). Reduced the monthly hosting bill by approximately 40-50% and long-term TCO by 50-70%. Built technical support for partners and for employees.

With development teams:

Continued all the things regarding the software development (see below for Head of Development): system design, infrastructure and platform services, control of the development process, etc.

Head of Development

Real estate web portal and aggregator; 80 employees.
August 2010 – July 2012 (2 years). Moscow, Russia.

Managed a department of front-end, back-end, database developers, and QA specialists. Expanded from 13 employees to 27 employees in 6 months. Built the processes to work and effectively communicate within a distributed team of web developers with 80% spread across the country.

Led a redesign to a three-tier service-oriented architecture (SOA; now known as “microservices”)—for scalability and maintainability—while keeping the existing systems up and running. Python, PHP, Oracle PL/SQL.

Directly managed some of the company’s long-term projects: mobile applications, back-office import/export/crawling systems, intranet content management, and infrastructure.

Senior Python Developer

Real estate web portal and aggregator; 50 employees.
February 2010 – August 2010 (7 months). Moscow, Russia.

Led a team of three Python developers: task management and prioritization, features and milestones planning, control of deadlines, mentoring, and advising for architectural solutions.

Python Developer

Real estate web portal and aggregator; 50 employees.
September 2009 – February 2010 (6 months). Moscow, Russia.

Designed from scratch a back-office system for automated data mining of third-party real estate data sources to the company’s web portal.  Python, Django.

Senior PHP Developer
Project 2000+

SaaS web site & application constructor (startup); 5 employees.
July 2008 – May 2009 (11 months). Moscow, Russia.

Developing a dating app. Mostly the backend: databases, ORM, caching, performance, scaling.

PHP Web Developer
Howard Design Studio

Web design and web development agency; 7 employees.
August 2007 – July 2008 (1 year). Moscow, Russia.

Developed studio’s content management system (CMS), and universal content-handling tools (typographic and similar). Built server and client sides of multiple websites.

PHP Web Developer / Self-employed

August 2005 – August 2007 (2 years).


Master’s Degree, Computer Science
Majored in Distributed Automated Systems.
Siberian State Technological University