Marcel Toben

As Head of Engineering for Economics & Experimentation, I am responsible for the full engineering scope of core infrastructure used across the company to steer the customer experience towards Zalando's strategic objectives. This includes established high performance engineered products, such as our A/B testing platform, as well as causal machine learning systems to steer the customer experience across the company based on customer lifetime value.

Growth at Contentful is a newly established cross-functional team with the mission of driving Contentful’s self-service business through product-led growth. The team has full responsibility for the strategy and performance of a significant part of Contenful’s business to make self-service an even bigger part of the Contentful success story. I helped to establish Growth as a team, discipline and methodology. I directly bootstrapped the processes around delivery in the group while aligning and merging the workstreams from product, design, data and development. I nurtured a culture of pragmatic experimentation and collaboration that was foundational for the team to achieve great business impact despite tight resources. The team is highly data-driven and focussed on delivery and impact while maintaining high standards of engineering excellence. I enjoy building and scaling high-performance engineering and data teams - I lead dozens of interviews and have hired top talent directly into the Growth Team. I support the development of my reports by mentoring and collaboratively setting ambitious but achievable goals while creating an environment of autonomy, ownership and accountability.

- Responsible for the in total 4 cross-functional engineering teams in product & growth, managing engineering managers - Directly responsible for the SEO growth team that has seen a +100% increase in Google traffic year on year by using SEO experiments and performance improvements on our 180+ million indexed landing pages - Involved in OKR and KPI planning for the teams and the whole organization - Creation of documentation and training material for engineering managers and individual contributors on 1:1 meetings, performance reviews, personal development, etc. - Contributing to the refinement of the IC and EM career growth paths - Definition of team-level and company-wide Engineering OKRs and initiatives to manage technical debt - Recruiting for Engineering Manager, Individual Contributor roles

- Leading a fast paced & high output growth team with a strong focus on user acquisition, retention, and engagement that is living the build measure learn loop. - Helped to improve user acquisition, retention, and engagement by optimizing products with rigorous experimentation (A/B Tests, Cohort tests etc.), tuning funnels and developing new features - Introduced growth accounting KPIs and metrics to measure both, breadth and depth of user engagement - Optimized the email and notification strategy - introduced a new smart notification system with embedded A/B/Cohort testing that makes sure that a user is receiving the right message, at the right time (timezone) on the most suitable channel (email, onsite notification, mobile app) - Java 8, Flink, Hive, MongoDB.

- Leading the data team with 4 engineers - Designed and implemented a system to discover, analyze and retrieve research metadata from the internet - written in Java and PHP - Connected thousands of university and other research / publication metadata repositories via OAI and other interfaces - Decentralized HTTP download service network with hundreds of nodes around the globe

- Product Manager for two cross-functional feature development teams - Shipped many of the ResearchGate core features, e.g. the Researcher Profile, Publications and Citation Products. - Launch of the new jobs / scientific recruiting product featuring a faceted search, keyword based targeting, promos, emails, an application tracking system via web and email and on-site.

- Design & implementation of the Activity Stream (Feed) - High available and high performant code written in Java, using Mongodb and Redis as storage. (JAVA) - Novel concept to optimize performance using multi layered bloom filters (JAVA) - Migrated a legacy SOAP J2EE service to a modern REST architecture - Implemented url query language and core classes and libraries for data abstraction (JAVA) - Designed the Experiment Framework for multi variant A/B tests based on a multi armed bandit algorithm - (PHP) - Helped to design and introduce a modular, component based, scalable and testable architecture for feature development. Refactoring of the legacy framework to use Composer, Symfony Components, Doctrine, Guzzle. (PHP), Introducing a component based frontend framework before (Javascript & PHP) - similar to React.js, just a few years earlier.

Leading the engineering as part of the architecture group, supporting and advising 50+ engineers. I was also responsible for building Buschfunk 2.0, the activity feed feature of the biggest social networks in Germany, studiVZ, meinVZ and schülerVZ. Design, architecture & implementation using Java, Redis, Voldemort, Hazelcast with high availability & high performance (12,000 requests per second - which was a lot in 2011)

VZ was the company behind the biggest social networks in Germany studiVZ, meinVZ and schülerVZ with over 18 million members. Senior software developer in the engineering core team, building the platform for feature development using PHP, Javascript and later Java.

Worked on the Goldman Sachs Securities Division Website (gs.de) (PHP / custom framework) - Development of new features, maintenance and bug fixes for gs.de and goldman-sachs.ch - Extended the data feed / live quote ticker feature - PHP and socket server in C - Design and implementation of an architecture and data model for a new generic financial instrument ticker service (real time push quotes) in cooperation with Goldman Sachs (Java, PHP, UML) Design and implementation of a generic framework to quickly bootstrap social network websites - Framework written in PHP based on Zend Framework 2, MySQL - Implemented all basic features: signup, login, user profiles, following, messaging, photos, posts, news, comments etc. - Launched a travel planning website / network and a social network for seniors in cooperation with two startups.