Kosmas Botsis, Developer in Athens, Central Athens, Greece
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Kosmas Botsis

Bio

Kosmas is a results-driven full-stack data engineer and analyst with over 10 years of experience turning raw data into actionable insights. He has extensive experience building scalable, efficient data processes. Kosmas specializes in end-to-end data solutions, including data ingestion, transformation, modeling, and visualization.

Portfolio

Wolt - Data & Analytics
SQL, Snowflake, dbt Cloud, Looker, Looker Modeling Language (LookML), Dagster...
Hema-Tec
SQL, BigQuery, Dataform, Google Apps Script, Google AppSheet, APIs, Paylocity...
Self-employed
SQL, MySQL, PostgreSQL, BigQuery, Snowflake, dbt Cloud, Dataform, JavaScript...

Experience

  • SQL - 15 years
  • PostgreSQL - 10 years
  • Data Engineering - 10 years
  • Data Analytics - 10 years
  • Looker Studio - 8 years
  • BigQuery - 8 years
  • Looker - 5 years
  • dbt Cloud - 4 years

Preferred Environment

Windows, Slack, Teams, Google, Visual Studio Code (VS Code), Jira, Notion, Google Meet, Zoom, Data Build Tool (dbt), Looker, BigQuery

The most amazing...

...enterprise data systems I've architected with BigQuery, dbt, and Looker became the foundation for strategic decision-making across organizations.

Work Experience

Analytics Engineer

2025 - PRESENT
Wolt - Data & Analytics
  • Designed and built a unified payment analytics infrastructure serving as the single source of truth for all payment reporting across multiple business verticals.
  • Migrated legacy mart-layer models from fragmented multi-table joins to a scalable unified architecture, improving maintainability and data consistency.
  • Implemented payment plan enrichment logic with multipayment detection, enabling accurate classification of complex payment structures.
  • Identified and resolved critical data quality issues, including systematic payment amount errors affecting specific markets.
  • Developed scalable deduplication key methodology for unified metrics reporting, replacing approaches that hit performance limits at scale.
Technologies: SQL, Snowflake, dbt Cloud, Looker, Looker Modeling Language (LookML), Dagster, Git, Data Modeling, Payments, Product Analytics, ETL

Analytics Engineer

2023 - PRESENT
Hema-Tec
  • Migrated a Google AppSheet back end from spreadsheets to BigQuery, creating a scalable data infrastructure for facility operations.
  • Built operational dashboards measuring employee performance metrics that enabled data-driven management decisions.
  • Automated payroll differential calculations and integrated with the Paylocity API, reducing manual processing time by 90%.
  • Developed an automated client reporting system that generates professional PDFs through API integration, eliminating manual report creation.
Technologies: SQL, BigQuery, Dataform, Google Apps Script, Google AppSheet, APIs, Paylocity, Teams, Business Intelligence (BI), Dashboards, Data Visualization, Data Analytics, Google BigQuery, Python, Databases, Google Sheets API, ETL, SQLx

Senior Analytics Engineer

2015 - PRESENT
Self-employed
  • Established data warehousing systems for 20+ clients, implementing BigQuery and Snowflake solutions that scaled with business growth.
  • Designed ETL/ELT processes using APIs and Webhooks that automated data integration from multiple sources for diverse industries.
  • Built advanced forecasting models and KPI tracking systems that enabled data-driven decision making for executive leadership.
  • Delivered comprehensive analytics projects including dashboard creation, data modeling, and workflow automation across 200+ engagements.
Technologies: SQL, MySQL, PostgreSQL, BigQuery, Snowflake, dbt Cloud, Dataform, JavaScript, Python, Looker, Looker Studio, Microsoft Power BI, Metabase, Data Engineering, Data Analysis, Webhooks, Business Intelligence (BI), Dashboards, Data Visualization, Data Analytics, Google BigQuery, Tableau, CSV, Data Quality Analysis, HubSpot API, Databases, Mixpanel, Product Analytics, Google Forms, Google Sheets API, Monday.com, Google Search Console, ETL, SQLx

Data Engineer

2022 - 2023
Tort Experts
  • Established a BigQuery data warehouse infrastructure that enabled efficient data processing and real-time analysis capabilities.
  • Leveraged dbt Cloud to build reliable data models that ensured data consistency and accuracy across all reporting layers.
  • Automated routine data processes and workflows, improving operational efficiency and reducing manual intervention by 70%.
Technologies: SQL, BigQuery, JavaScript, Looker, Google Apps Script, Stitch Data, Monte Carlo, dbt Cloud, Dashboards, Data Visualization, Data Analytics, Google BigQuery, Google Forms, Google Sheets API, Google Search Console, ETL

Analytics Engineer

2018 - 2021
Ergeon
  • Established a BigQuery data warehouse infrastructure that centralized disparate data sources into a unified analytics platform for the entire organization.
  • Built comprehensive KPI tracking dashboards that enabled executive leadership to monitor business performance in real-time.
  • Streamlined data workflows by automating routine tasks, increasing team productivity and eliminating manual reporting bottlenecks.
Technologies: BigQuery, PostgreSQL, ETL, Looker Studio, Google Sheets, Key Performance Indicators (KPIs), SQL, Data Analysis, Financial Analysis, Pipedrive API, Jira, Business Intelligence (BI), Dashboards, Data Visualization, Data Analytics, Google BigQuery, Product Analytics, Google Forms, Google Sheets API

Data Analyst

2013 - 2015
Black Box
  • Maintained accuracy within the international product sales database, covering multiple subsidiaries across global markets.
  • Created forecasting models that predicted regional sales performance and identified growth opportunities across markets.
  • Developed automated reporting processes that streamlined corporate reporting workflows and reduced manual errors.
Technologies: MySQL, Microsoft Excel, Pricing, Financial Analysis, Data Analysis, Data Analytics, Product Analytics

Experience

BigQuery Data Warehouse Implementation for SaaS Company

I led a complete data infrastructure transformation for a growing SaaS company, migrating from fragmented spreadsheet-based reporting to a unified BigQuery data warehouse. The project involved designing and implementing ETL pipelines using dbt Cloud to process customer data, subscription metrics, and financial transactions. Additionally, I built comprehensive Looker Studio dashboards tracking key business metrics including MRR, churn rates, and customer acquisition costs. The solution reduced reporting time from days to minutes while providing real-time visibility into business performance, enabling data-driven decision making across all departments.

Payroll Automation with API Integration

I developed an end-to-end payroll automation system for a healthcare facility management company processing 1,000+ employee payments monthly. This involved creating complex algorithms based on facility performance metrics to calculate shift differentials, overtime rates, and bonus structures.

I also integrated the solution with the Paylocity human resources information system via API, eliminating 90% of manual data entry and reducing payroll processing errors to zero. Additionally, I built real-time monitoring dashboards to track payment status and generate compliance reports. The system saved 40+ hours weekly, ensuring accurate, timely payments and regulatory compliance.

Real-time Employee Performance Tracking System

I architected a comprehensive analytics platform to measure employee productivity across multiple facility locations. I also migrated data collection from Google Sheets to a BigQuery back end, supporting a mobile Google AppSheet application used by 500+ field employees. I implemented Dataform transformation pipelines to standardize performance metrics and create rolling averages for trend analysis. Additionally, I built executive dashboards displaying real-time KPIs, including task completion rates, quality scores, and efficiency metrics. The platform enabled managers to identify top performers, optimize scheduling, and improve operational efficiency by 25%.

Education

2010 - 2012

Master’s Degree in Business Administration (MBA)

University of Kentucky - Athens, Greece

2002 - 2007

Bachelor's Degree in Business Administration

University of West Attica - Athens, Greece

Skills

Libraries/APIs

Google Sheets API, SQLx, REST APIs, WooCommerce API, QuickBooks API, HubSpot API, Pipedrive API

Tools

BigQuery, dbt Cloud, Google Sheets, Google Analytics, Slack, Looker, Microsoft Access, FileMaker, Retool, Microsoft Power BI, Zapier, Stitch Data, Tableau, Google Forms, Jira, Notion, Google Meet, Zoom, Microsoft Excel, Paylocity, Git

Languages

SQL, Google Apps Script, Python, JavaScript, Snowflake, Looker Modeling Language (LookML)

Paradigms

ETL, Business Intelligence (BI)

Platforms

Dataform, Airbyte, Visual Studio Code (VS Code), Google Ads, Bing Ads, Shopify, Mixpanel, WordPress, Windows, Google AppSheet

Storage

Google Cloud, Databases, MySQL, PostgreSQL

Frameworks

Django

Other

Looker Studio, Data Engineering, Data Analytics, Financial Analysis, Teams, Dashboards, Data Visualization, Google BigQuery, CSV, Data Quality Analysis, Metabase, Fivetran, Google Cloud Functions, Product Analytics, Google Search Console, Business, Finance, Google, Key Performance Indicators (KPIs), Data Analysis, Pricing, Monte Carlo, APIs, ELT, Data Modeling, API Integration, Database Automation, Financial Modeling, Data Warehousing, Performance Analysis, Data Build Tool (dbt), Webhooks, Dagster, Payments, Monday.com

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