Drazen Zaric
Verified Expert in Engineering
Data Scientist and Machine Learning Developer
Belgrade, Serbia
Toptal member since June 22, 2019
Drazen is a data scientist and data engineer with over seven years of experience building analytics infrastructure, machine learning, and data analysis. He has extensive experience in big data, machine learning, and web development. He has worked with notable companies such as Slack and Microsoft, and built products used by millions of users.
Portfolio
Experience
- Data Science - 10 years
- Python - 8 years
- Deep Learning - 4 years
- Natural Language Processing (NLP) - 4 years
- Machine Learning - 4 years
- Large Language Models (LLMs) - 2 years
Availability
Preferred Environment
Vim Text Editor, Python, Linux, MacOS
The most amazing...
...project I've built was an analytics infrastructure for a product with 150 million users.
Work Experience
Senior Data Scientist
Delivery Hero
- Led the effort to optimize the processing and storage of a large-scale customer network graph. Reduced costs by 10x and feature calculation latency by 120x.
- Developed a graph neural network model for courier fraud.
- Developed and maintained fraud models for payment and refund fraud. Improved a cash payment risk model to 3x its financial value.
Senior Python Developer
Property Guard
- Developed a scalable, distributed web crawler using Python, Flask, Redis on DigitalOcean cloud.
- Created an autoscaling system leveraging DigitalOcean Droplets and Docker.
- Developed and tested several components of the distributed system, including the orchestrator service, Redis queue, ELK monitoring, and DigitalOcean and Ansible infrastructure provisioning.
Data Scientist
Teespring
- Collaborated as a part of the data team. Developed dashboards in Tableau and data reports with Redash; worked on migrating from Redshift to Snowflake.
- Supported the commercial and partnership teams with data insights.
- Developed an interactive real-time map visualization of Teespring sales with JavaScript and Mapbox.
Analytics Consultant
Freelance Consultant
- Collaborated with small companies on establishing their data infrastructure, discipline, and teams.
- Assessed existing processes, available data, and infrastructure.
- Planned for future growth in terms of product and the team.
- Helped with descriptive and predictive user behavior models, segmentation, and A/B testing.
Product Manager
Nordeus
- Led the team in developing Golden Boot, a game for a then-new platform called Facebook Instant Games. This product grew from an idea to over 10 million players in four months.
- Oversaw product and project management, back-end development, data analysis, and game design within an Agile team.
- Developed high-performance algorithms for matchmaking.
- Created a distributed push notifications system backed by a Hadoop data warehouse and a machine learning model for user churn.
Data Scientist
Nordeus
- Developed internal data products. Designed, developed, and deployed optimization algorithms for in-game tournament generation.
- Created machine learning models for anomaly detection, product performance, and user behavior prediction tools for optimizing marketing campaigns.
- Maintained and improved a custom, in-house BI tool.
- Supported product managers, game designers, and user acquisition teams with analyses and insights.
Data Engineer
Nordeus
- Developed and maintained an in-house ETL system and data warehouse on top of Hadoop and Impala for TopEleven, an online game with over 150 million players.
- Transitioned a single PostgreSQL instance to an in-house Hadoop cluster solution.
- Designed and wrote data import, SQL transformations, and oversaw the data quality.
- Integrated data from internal and third-party data sources.
- Scaled data warehouse and processes from a single product to multiple products.
Software Development Engineer
Microsoft
- Developed the PDF Reflow feature for Microsoft Word 2013.
- Designed algorithms for converting a PDF into an editable DOCX document.
- Implemented and evaluated machine learning models for identifying parts of a PDF document.
Experience
Blogboard
https://blogboard.ioI worked on the back end, front end, data pipelines, and machine-learning systems. I used NLP/LLMs, PyTorch, Python, Elasticsearch, PostgreSQL, and Vue.js.
Top Eleven by Nordeus
https://www.topeleven.com/Upvote for Slack
https://upvote.chatUpvote is a small, profitable product. I developed the app end-to-end, including the back end, front end, Slack API integration, UX and UI design, and marketing.
Selecta: An Amarok Player Extension
https://github.com/drazenz/SelectaImproved Heatmaps in Python
https://github.com/drazenz/heatmapSimilar to what you can easily get in Tableau using a size parameter, here you can have a square as a parameter depending on the field value.
Described in detail in this blog post: https://towardsdatascience.com/better-heatmaps-and-correlation-matrix-plots-in-python-41445d0f2bec
Education
Master's Degree of Science in Computer Science
University of Novi Sad - Novi Sad, Serbia
Bachelor's Degree in Computer Science
University of Novi Sad - Novi Sad, Serbia
Certifications
Product Management Program
UC Berkeley Executive Education
Skills
Libraries/APIs
Scikit-learn, Pandas, NumPy, Vue, PyTorch, Redis Queue, Scikit-optimize, SciPy
Tools
Apache Impala, Tableau, Git, Ansible, Vim Text Editor, GitHub
Languages
Python, SQL, C++, JavaScript, Snowflake, Java, Bash, Python 3
Frameworks
Flask, Hadoop, LightGBM
Platforms
Linux, MacOS, Apache Kafka, Web, DigitalOcean, Docker
Storage
PostgreSQL, Aerospike, Redshift, Elasticsearch, MySQL, Databases, Database Modeling
Paradigms
Agile, Scrum, ETL
Other
Data Engineering, Data Science, Machine Learning, Algorithms, Data Analysis, Database Analytics, Neural Networks, Deep Learning, Natural Language Processing (NLP), Data Visualization, Web Development, Optimization, eCommerce, Large Language Models (LLMs), Big Data, Front-end, Back-end, Writing & Editing, Software Engineering, Data Analytics, Dashboard Design, Product Management, App Product Management, Development, Lean Project Management, ETL Tools, ETL Testing, ETL Development, APIs, Dashboards, Interactive Maps, Data Modeling, Scraping, User Experience (UX), User Interface (UI), Data Scraping, Web Scraping, Graphs, Graph Neural Networks, Fintech, Fraud Detection, Message Queues, App UX, Innovation, B2C Marketing, Electrical Engineering, Hardware Design, SEO Tools, Content Writing, Technical Writing, Information Retrieval, Music Information Retrieval (MIR), Open Source, Value Innovation, Open-source LLMs, Large Language Model Operations (LLMOps), Machine Learning Operations (MLOps)
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