Aleksandra Woźniak, Developer in Munich, Germany
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Aleksandra Woźniak

Verified Expert  in Engineering

Startups Developer

Munich, Germany
Toptal Member Since
July 31, 2018

Aleksandra is an entrepreneur, engineer, and ex-startup CTO with nine years of experience working for both large corporations (Google, Elsevier, Capgemini) and start-ups. Her expertise lies in building Java back-ends for web applications and in big data technologies. Aleksandra is also a co-founder of Cleo, a virtual personal finance assistant, for which she developed natural language and financial data processing modules.


Cleo AI Ltd.
PostgreSQL, SCSS, HTML5, JavaScript, Heroku, GitHub, Git...
Elsevier Limited
Kanban, Pair Programming, Test-driven Development (TDD), Apache Spark, Docker...
Geonomics Global Games
HTML, SCSS, Domain-driven Design (DDD), Code Review...




Preferred Environment

Git, IntelliJ IDEA, Ubuntu Linux

The most amazing...

...project I've developed is Cleo, a personal finance assistant in FB Messenger that analyses users' spending, provides tips, and answers money-related questions.

Work Experience

Co-founder and CTO

2015 - 2017
Cleo AI Ltd.
  • Grew the business from 0 to tens of thousands of users in two years and raised £2.5 million for the business through private equity investors.
  • Served as the sole developer for one year. I developed a web application, SMS interface, and Facebook Messenger chatbot Cleo, the company's flagship product.
  • Implemented modules for analyzing a user's payment transaction history, detecting spending patterns and providing recommendations on how user's spending be optimized.
  • Implemented natural language processing functionality for Cleo chatbot.
  • Recruited and managed the founding engineering team. Led the technical product design and development.
  • Set and executed the technical strategy for the company, aligning product engineering with business goals.
Technologies: PostgreSQL, SCSS, HTML5, JavaScript, Heroku, GitHub, Git, Facebook Messenger API, Ruby on Rails (RoR), Ruby, Chatbots

Java Developer (Big Data team)

2015 - 2015
Elsevier Limited
  • Developed Hadoop jobs for aggregating and processing sales data from various business units of Elsevier and creating financial reports.
  • Designed and prototyped central big data processing system for Elsevier, enabling access and processing functionalities for data sets across different departments.
  • Gathered requirements and performed estimations of the internal big data processing system.
Technologies: Kanban, Pair Programming, Test-driven Development (TDD), Apache Spark, Docker, Amazon Web Services (AWS), Hadoop, Java, Data Processing, Big Data

Java/Full-stack Developer

2013 - 2015
Geonomics Global Games
  • Planned, designed, and implemented data aggregation and financial reporting software for a global map-based lottery game platform.
  • Maintained and enhanced the game's financial reporting and data aggregation modules.
  • Implemented registration and payment flow for the mobile version of GeoLotto game.
  • Designed and implemented a custom content management system for the game's website.
  • Introduced the domain-driven design paradigm to the development process, performed a thorough review of the codebase, and created a refactoring plan to transform the initial domain model into a more expressive one.
Technologies: HTML, SCSS, Domain-driven Design (DDD), Code Review, Test-driven Development (TDD), Unit Testing, Google Web Toolkit, Apache Wicket, Hibernate, Spring MVC, Java

Chief Architect's Technical Assistant/Software Developer Intern

2012 - 2013
Hadapt Polska Sp. z o. o.
  • Investigated and tested new approaches to extend Hadapt's flagship product, a big data analytics platform that integrates SQL with Hadoop.
  • Prototyped new approaches to integrate text indexing with the platform, using Apache Lucene and Apache Solr. Tested the prototypes for performance.
  • Created end-to-end test architecture for Hadapt platform. Designed and implemented a suite of stress and scalability tests.
  • Managed team of three testers.
Technologies: Amazon Web Services (AWS), IntelliJ IDEA, Eclipse, Apache Solr, Python, Bash, Gradle, Apache Hive, Hadoop, Java

Software Developer Intern

2011 - 2012
Google Switzerland GmbH
  • Implemented usability enhancing features for Google Flight Search and Google Hotel Finder.
  • Introduced new search types for Hotel Finder: searching by hotel name and searching by address.
  • Implemented an optimisation algorithm for efficient label placement on the Google Flights map.
Technologies: Perforce, Git, Eclipse, Guice, Google Web Toolkit, Java

Software Developer Intern

2010 - 2011
Capgemini Polska Sp. z o. o.
  • Tested an interface and behavior of an application for a leading logistics company.
Technologies: HP Quality Center (QC), Subversion (SVN), HTML

Java Web Developer

2009 - 2010
Wspólny Rynek Medyczny Sp. z o. o.
  • Implemented an internationalization feature for -- an online database of Polish medical institutions.
  • Prepared mechanisms for transforming rough XML data of medical institutions into HTML documents.
Technologies: PostgreSQL, SQL, Apache Ant, Subversion (SVN), CSS, HTML, JUnit, Eclipse, Apache Wicket, Cocoon, XML, XSLT, Java

Teaching Java Professionally

In cooperation with the ProLearning Training Centre, I conducted two intensive 5-day-long Java courses for IT professionals: "Introduction to programming using Java" and "Advanced Java".
2010 - 2013

Master of Science Degree in Computer Science

University of Wrocław - Wrocław, Poland

2007 - 2011

Bachelor of Science Degree in Mathematics

University of Wrocław - Wrocław, Poland

2005 - 2009

Bachelor of Science Degree in Information Technology

Poznań University of Technology - Poznań, Poland


Facebook Messenger API, Cocoon, Spring REST, jQuery, Apache Lucene


IntelliJ IDEA, Git, Apache Maven, GitHub, Gradle, Perforce, Subversion (SVN), HP Quality Center (QC), Apache Ant, Apache Solr


Spring, Hibernate, Spring MVC, JUnit, Ruby on Rails (RoR), Hadoop, Apache Spark, Google Web Toolkit, Guice, Spark, Apache Wicket


Test-driven Development (TDD), Unit Testing, Refactoring, Dependency Injection, Pair Programming, Kanban


Java, Ruby, SQL, HTML, Bash, XSLT, XML, CSS, JavaScript, HTML5, SCSS, CSS4, Python


PostgreSQL, Relational Databases, Apache Hive


Amazon Web Services (AWS), Heroku, Ubuntu Linux, Docker, Eclipse, Linux


Startups, Code Review, Lean Startups, Fintech, Big Data, SOLID Principles, Chatbots, Data Processing, Domain-driven Design (DDD)

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