Chrisovalantis Efthymiou

• Developing and maintaining backend components of high-availability lottery and betting platforms using Python and Oracle PL/SQL, within a small engineering team.
• As Senior, overseeing platform backend work and mentoring on design and code quality.

Python 2 → 3 Migration

• Played a key role in migrating the platform's large legacy codebase from Python 2.7 to 3.11 — identifying breaking changes, refactoring components, and keeping production stable throughout.
• Continued the effort up to Python 3.14, taking it to production with a smooth, incident-free rollout.

• Built and maintained time-sensitive services processing external providers' data with Python and MongoDB, running on Docker and Kubernetes with Helm-managed deployments.

• Started with parallel SQL extraction from Oracle into Google BigQuery for analytics and reporting.
• Redesigned the pipeline as an asynchronous Python service with an orchestrator–worker architecture.
• Currently improving the process with data reconciliation between source and warehouse.

• Built integration services in Python, initially deployed as Azure Functions.
• Migrated the heavier and longer-running jobs to Azure Container Apps as the workload outgrew serverless timeouts.
• Owned deployment, logging and monitoring in Azure.

• CSV files land in OneDrive → Python service reads them directly, normalises and validates, then pushes into BC via its REST API.
• Handles retries and idempotent re-imports.

• Invoice PDFs in OneDrive → Python extracts them → Anthropic API turns unstructured invoice content into structured data (vendor, line items, totals).
• Staged into a SQL database, then a validation layer runs — rate-card matching, structural checks, amount reconciliation — before pushing into BC.
• Replaced a previously manual data-entry step.