Sandra Kozomara, Developer in Belgrade, Serbia
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Sandra Kozomara

Verified Expert  in Engineering

Database Developer

Belgrade, Serbia
Toptal Member Since
June 18, 2020

Sandra brings 20+ years of experience in the development of competitive location and business intelligent systems enabling market opportunity analysis, high-level roll-out strategy, workforce management, operational reporting, and KPIs tracking. She successfully integrates data from companies OSS/BSS, mobile apps, DWH, machine learning models, and external services for the purpose of reporting and data visualization. She has eight years of management experience and is a certified Scrum Master.


Stada IT Solutions
LeanIX, ITIL V3 Foundation Certified, Azure Boards, Management...
Stada IT Solutions
Azure Boards, Snowflake, Azure Data Factory, Qlik Replicate, Microsoft Power BI...
Hyperoptic, Ltd.
Jira, QGIS, GeoServer, PostgreSQL, SQL, GIS, qTest Manager, Design...




Preferred Environment

QGIS, GIS, Oracle, Azure Boards, SQL, PostgreSQL, Database Design, Data Engineering, Team Management

The most amazing...

...thing I've introduced new analytical technologies to three companies, upskilling people, implementing new processes, and enabling companies become data driven.

Work Experience

Enterprise Application Architect, LeanIX Steward

2023 - PRESENT
Stada IT Solutions
  • Led LeanIX implementation project, overseeing project planning, execution, and monitoring. Ensured adherence to project scope, timeline, and quality standards. Communicated directly with stakeholders and implementation partners and managed project risks.
  • Established LeanIX metamodel setup, roles, responsibilities, and dashboards. Onboarded over 250 people to LeanIX through workshops, regular open doors, one-on-one sessions, and documentation.
  • Identified all Stada applications through legacy application repository, country workshops (50+ countries), business domain workshops, and meetings with application owners.
Technologies: LeanIX, ITIL V3 Foundation Certified, Azure Boards, Management, IT Project Management, Microsoft Excel

Head of Data Hub

2021 - 2023
Stada IT Solutions
  • Established a new cloud-based global Data Hub, serving as the one source of truth for reporting across Stada Group. Utilized Snowflake, ADF, and Qlik Replicate with CI/CD pipelines in place. Implemented new processes around the new environment.
  • Led the migration of three legacy MS SQL/SSIS DWHs to new Data Hub technologies. Orchestrated migration of data and projects developed by IT BI teams. Supported over 50 business users in migrating self-service reporting to the Data Hub.
  • Oversaw the migration of existing BI tools from on-premise to Azure, including Tableau, Power BI, and Alteryx.
  • Led team development to empower members with the necessary skills to use new toolsets and procedures effectively. Managed a diverse, remote international team, including internal staff and external consultants, such as data architects, data engineers, and BI developers.
  • Provided strong support to BI self-service, including creating data products with ownership, implementing data sharing, and establishing and supporting BI self-service communities through training programs and data catalog initiation.
  • Implemented Scrum as a certified scrum master to organize, prioritize, and monitor work. Ensured the team understood company goals and how their work contributes while setting SMART KPIs.
Technologies: Azure Boards, Snowflake, Azure Data Factory, Qlik Replicate, Microsoft Power BI, Tableau, Alteryx, Scrum Master, Agile, Management, IT Project Management, Team Management, Data Analysis, Microsoft Excel, Business Intelligence (BI), Data Visualization

Manager of Location Intelligence Team

2018 - 2021
Hyperoptic, Ltd.
  • Led the development of a competitive edge system for top-level roll-out strategy planning.
  • Acted as the business analyst, data model architect, and manager for a multidisciplinary team consisting of database developers, Java developers, QA engineers, DevOps engineers, ML specialists, and network graph specialists.
  • Introduced the quality assurance role into the location intelligence (LI) team. Implemented a software testing lifecycle, bug tracking process, QA tools, and QA onboarding. Automated testing for the most critical data sources was done via database procedures.
  • Led DWH and LI integration on the LI side. By dividing KPI ownership and sharing relevant data sources, we enabled the data definition change to be implemented on one yet available system to both. Updated core LI ETL.
  • Conducted data integration and analytics for various purposes, including address market, competitive analysis, fieldwork tracking, planned versus built cable meters, and other KPI reporting.
  • Integrated diverse data sources, such as spatial data, internal and external datasets, and mobile app data.
  • Implemented routing capabilities into the database to make smart decisions on where to build a cable network, estimate the cost versus benefit of planned networks, and prioritize work.
Technologies: Jira, QGIS, GeoServer, PostgreSQL, SQL, GIS, qTest Manager, Design, Scrum Master, Agile, Database Design, Data Engineering, Management, IT Project Management, Team Management, Data Analysis, Microsoft Excel, Business Intelligence (BI), Data Visualization

GIS Manager

2017 - 2018
Hyperoptic, Ltd.
  • Performed complex spatial analyses collaborating with business stakeholders and helped drive smart business decisions, including business opportunities, profit estimates of potential contracts, top-level network planning, and network development progress KPIs.
  • Worked with technical teams to integrate data from internal end external data sources to GIS platform, including telecom infrastructure, address database, customers, sales opportunity and sales data, optical network planning, and field operation progress.
  • Introduced and organized a new GIS team, onboarded and upskilled eight fresh graduates to Python developers, database developers, and GIS specialists. Mentored and provided growth opportunities, increasing team capability and GIS platform stability.
Technologies: GeoServer, QGIS, PostgreSQL, SQL, GIS, Jira, Design, Database Design, Data Engineering, Management, Team Management, Data Analysis, Microsoft Excel, Business Intelligence (BI), Data Visualization

GIS Specialist

2016 - 2017
Hyperoptic, Ltd.
  • Introduced GIS to the company, establishing open-source tools such as PostgreSQL database, GeoServer, and QGIS as GIS environments. Collaborated closely with web development teams to create a web map for a wider company audience.
  • Established ELT process to integrate data from internal BSS (transactional MySQL database) and data from external sources to PostgreSQL. New data sources were created to analyze sales, market opportunities, and quarterly and yearly network planning.
  • Established reporting in cooperation with the business, utilizing QGIS to present data in the form of tables or maps. Increased the number of location-based analytics stakeholders through training and support.
Technologies: QGIS, GeoServer, PostgreSQL, SQL, GIS, Jira, Design, Database Design, Data Engineering, Data Analysis, Microsoft Excel, Business Intelligence (BI), Data Visualization

Head of GIS and PAK Office

2015 - 2016
PE Post of Serbia
  • Oversaw the postal address system and code maintenance, including standardizing and validating legal persons' address data according to the post's address system.
  • Participated in the creation of the National Address Standard as a member of the technical committee of the NSDI, BeoGIS project.
  • Created a three-tiered Oracle-Delphi application using database clusters to validate millions of addresses.
Technologies: TortoiseSVN, PHP, MapServer, MapInfo, MapBasic, Oracle, SQL, PL/SQL, GIS, Management, Design, Oracle Spatial, Database Design, Data Engineering, Team Management, Data Analysis, Transportation & Shipping, Microsoft Excel, Business Intelligence (BI), Data Visualization

Head of Spatial Data Analysis Office

2008 - 2015
PE Post of Serbia
  • Created a GIS framework for the Public Enterprise Post of Serbia, the central point of reference for GIS architecture, development, user onboarding, and other GIS-related questions.
  • Integrated data from company internal and external data sources, forming Location DWH. Conducted data analysis for KPI tracking and process optimization.
  • Collaborated with users to analyze business requirements: conducted interviews, performed business analysis, developed specifications, defined rules and logic, created implementation plans, and documented findings.
  • Managed the project "Implementing GIS" with 70 people to create one of the largest GIS databases in Serbia for the postal address database. Developed a performance monitoring system to track the progress and a data quality monitoring system.
  • Created commercial services based on an address database and service sales. Engaged directly with clients.
Technologies: TortoiseSVN, PHP, MapServer, MapInfo, MapBasic, Oracle, SQL, PL/SQL, GIS, Management, Delphi, Design, Oracle Spatial, Database Design, Data Engineering, IT Project Management, Team Management, Data Analysis, Transportation & Shipping, Microsoft Excel, Business Intelligence (BI), Data Visualization

Full-stack Developer, from Junior to Senior

1998 - 2008
PE Post of Serbia
  • Worked on full-stack development of multi-tier applications using Oracle and Delphi technologies. Implemented business logic within the database using PL/SQL.
  • Supported postal delivery and HR business processes by gathering and analyzing user requirements, designing a database in 4NF, developing applications, testing, deploying, user onboarding, and documenting.
  • Acted as a mentor to new team members, offering advice and feedback to help them grow and excel in their roles.
Technologies: Delphi, Oracle, SQL, PL/SQL, Design, Database Design, Data Engineering

Implementation of a New Cloud-based Data Hub and BI for a Pharmaceutical Company

As the team manager, I led the implementation of a new cloud-based global Data Hub for a pharmaceutical company, serving as the one source of truth for reporting across the Stada Group.

There were five main goals of the project:
1. Establish a new cloud DWH with processes around it, utilizing Snowflake, ADF, and Qlik Replicate, with CI/CD pipelines in place.
2. Migrate BI tools to the cloud, including Power BI, Tableau, and Alteryx.
3. Upskill data engineers and BI developers to use new tools and processes.
4. Migrated three legacy DWHs and dashboards to a new cloud BI environment
5. Develop BI self-service community and support businesses in the migration of their projects.

My role was to lead the project, manage stakeholders and external consultants, and organize the team. Technical lead for process and tool setup was done by data architects.

Creating Location Intelligence for a Telecommunication Company

As the main developer, technical lead, and team manager, I created Location Intelligence for a telecommunication company by setting up a Location DWH and Location BI for data visualization.

Location DWH was built using PostgreSQL and ELT processes, with transformations done using SQL procedures (strong database knowledge). Data sources integrated within DWH included internal data from companies BSS/CRM, mobile data from fieldwork, British Telecom asset API, Royal Mail Postcode, Ordnance Survey address database, Census data, Competitor data, and Road work.

On top of DWH, I created Location BI to present analyzed data and KPIs such as customer density, competitor mapping, efficient route planning, and network development progress KPIs. I also used open-source technologies, such as Geoserver, QGIS, and web GIS.

I started as a one-person team and later formed a team of juniors for data visualization, maturing the team with senior database developers to maintain the growing DWH.

Creating Spatial Analytics for a Post Office

As the main developer, technical lead, and manager, I integrated the Oracle Spatial database with various data sources to enable maximum analytics capabilities of location data in PE Post of Serbia.

These data sources were collected from different systems, including:
• Post counter application to track productivity at the person and post office levels and monitor customer traffic to plan post office marketing activities
• Car tracking system for a vehicle usage KPI at planned working hours and misusage during unplanned working hours. Also, for KPIs regarding post-handover at exchange points.
• Postman mobile app for tracking KPIs regarding working hours, mileage, application usage, and mobile data quality.
• SAP for financial KPIs and many others.

Implementation of a Geographic Information System
As the project manager and full-stack developer for the Implementing Geographic Information System project, I oversaw a team of 70 people to create one of the largest GIS databases in Serbia.

The database included an address system with house numbers and geographic coordinates, making it the most comprehensive address system in the country. Additionally, it was the first system to enable geo-positioning hierarchy address elements such as municipalities, settlements, streets, PAK, and house numbers. As part of the project, we also created two additional systems for data quality and performance monitoring, which enabled the creation of new GIS postal services.

Smartass – Analytical Tool for Discovering the Most Profitable Routes

Top-level roll-out strategy tool for finding the most profitable route to lay optic cable in. The tool compared the cable length as an expense, with estimated revenue based on the count of households next to the route and the probability of signing a contract with the company.

This project involved combining expertise from the Faculty of Mathematics to provide an algorithm to search for all potential routes within 400,000 km of roads, machine learning experts to provide an ML algorithm for predicting contract signing, internal database engineers to prepare data for the two algorithms and Java developer to bring all the tools together.
My role in the project was to design a database, manage the project, and be the team lead.

Creation of Delivery Areas for Parcels Based on Analytics of Historical Data
The project aimed to distribute a uniform workload among parcel delivery couriers via a vehicle, especially in dense areas (tall buildings or business centers) and dispersed areas that take a long time to reach. To address this issue, I used a 1-year history of vehicle tracking data to create stopover points with two values: time needed to get to the point and time spent on the point. Based on this information, together with other information like post office location and parcel count, parcel delivery managers created 80-minute areas. This enabled us to create a uniform workload for regular (8 hours) and weekend (6 hours) shifts while preventing two different mail carriers from going to the same or similar address on the same day.
My role in this project was database engineer, providing full data analytics and visualization of a map.

GIS Portal of PE Post of Serbia
To enable citizens to obtain detailed information from postal data on maps, I led the creation of a postal web GIS portal. The portal allows users to view address data and postal objects, such as post offices, cash machines, and delivery areas, which can be searched by specific parameters. My role in the project was as project lead and database developer.

Implementation of New Postal Address Code
The Serbian post office created a new postal address code (PAK) and needed to translate all addresses to the new PAK. My role in this project was to be the main full-stack Oracle/Delphi developer to fully support the project.

There were three main outputs of the project:
1. Create an application for collecting and maintaining a postal address system, including municipalities, settlements, streets, and PAK, in correlation to the address system.
2. Develop an application for implementing new principles in defining the postman delivery area and itinerary based on the new PAK. Also, postman productivity KPI tracking based on the new PAK.
3. Create an application for legal person address validation, enabling new service for PE Post of Serbia customers for address data validation. This application enabled holding, validating, and assigning PAK to each billing address of our customer (millions of addresses). With PAK assigned to the delivery address, customers received discounts in postal services.
1992 - 1998

Master of Mathematics Degree in Computer Science

Faculty of Mathematics, University of Belgrade - Serbia


Use SurveyMonkey to Create a Survey and Analyze Results



Certified LeanIX Practicioner

LeanIX Academy


Professional Scrum Master I (PSM I)



Smars School


Oracle Spatial: Essentials

Breza Softver Engineering


GIS, MapInfo, Microsoft Excel, Jira, qTest Manager, TortoiseSVN, Qlik Replicate, Microsoft Power BI, Tableau, SurveyMonkey


Delphi, SQL, Delphi 7, PHP, Snowflake


Management, Agile, Database Design, Business Intelligence (BI)


Oracle, MapServer, Alteryx


PL/SQL, PostgreSQL, GeoServer


MapBasic, Design, QGIS, Azure Boards, LeanIX, Scrum Master, LeanIX EAM Practitioner, Oracle Spatial, Data Engineering, Team Management, Data Analysis, IT Project Management, Transportation & Shipping, Data Visualization, Azure Data Factory, ITIL V3 Foundation Certified, IT Service Management (ITSM), Surveys

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