Tomasz Jarosz

Delivering ledger services and counterparty exposure reporting in a regulated environment - designing solutions for data integrity, traceability (audit trails), and production-grade reliability, while reducing legacy risk by moving critical logic out of the database into testable services.

• Built a new regulatory exposure reporting application (Java 21 + React) running on Azure Functions, delivering end-to-end features from backend services to UI.
• Led the modernization of legacy DB-driven business logic by migrating complex Sybase ASE stored procedures to Java 21 services, making core calculations testable, reviewable, and safer to change.
• Re-engineered a high-impact instrument pricing & FX rates module: moved untested, tightly coupled SQL logic into clean Java components and introduced regression tests to ensure behavioral parity with legacy outputs.
• Converted multiple reporting workflows from SQL scripts into application-level pipelines, improving consistency, observability, and operational supportability.
• Drove large-scale refactoring and decoupling: reduced vendor/DB coupling, introduced clearer module boundaries and domain abstractions, and systematically paid down technical debt.

Skills: Java · Spring Boot · JavaScript · React · Sybase · Azure Cosmos DB · Microsoft Azure · SQL

Intensive, hands-on 4-week program hosted at The Hong Kong Polytechnic University (PolyU) and delivered by core Parity Technologies engineers, Web3 Foundation experts, and university faculty.

• Highly selective cohort: ~30 developers selected (from ~50 participants globally) out of hundreds of applicants.
• Graduated with Excellence Certificates: Substrate (Top 10 / ~30) and FRAME (Top 16 / ~30).
• Deep engineering focus: Rust, Substrate runtime development, FRAME pallets, XCM, consensus (BABE/GRANDPA), and P2P networking — with emphasis on production-grade design and correctness.
• Capstone: Built a Uniswap v2–style AMM DEX on a custom Substrate-based Polkadot parachain — implemented liquidity pools (add/remove), swaps (x*y=k), LP shares/tokens, and fee accounting as FRAME pallets, with tests and full runtime integration.

Skills: Rust · Substrate · Frame · Blockchain · Polkadot · Cryptography · Consensus Algorithms

Built an ML-driven pricing platform for airlines (incl. Etihad) to forecast booking demand and optimize ticket prices to maximize revenue, using linear regression models and supporting data pipelines.

• Developed and maintained data-heavy processing in Python + Apache Spark, integrating services built with Java/Spring and delivering UIs in JS/React.
• Migrated data processing from MongoDB to an OLAP-oriented approach, improving analytical workloads and enabling efficient multidimensional processing in Spark.
• Profiled and optimized Spark jobs on AWS EMR to improve cluster utilization and performance (runtime/cost reductions where applicable).
• Collaborated with PMs/stakeholders to define scope, milestones, and delivery plans; translated requirements into maintainable solutions.

Skills: Java · Python · Spring Boot · Apache Spark · Amazon EMR · MongoDB · AWS

Developed and maintained a Call Centre application supporting daily operations (backend + frontend).

• Implemented key migrations: OracleDB → PostgreSQL (performance/cost), GWT → React/JS (faster development + modern UI), and services/components to cloud (AWS / GCP).
• Delivered UX improvements that increased agent efficiency.
• Participated in on-call rotation and incident handling to maintain high availability.

Skills: Java · Kotlin · JavaScript · React · GWT · PostgreSQL · Oracle SQL · AWS · GCP

Progressed from Intern to Mid-level engineer, taking ownership of larger modules over time.

• Built Spring Batch pipelines processing IATA/ATPCO data for reliable ingestion and timely availability.
• Developed internal tools for managing taxes, fares, and airline rules in a travel booking ecosystem.
• Maintained and supported production scheduling via AutoSys jobs (monitoring, troubleshooting, fixes, and incident-driven changes).
• Collaborated with BAs/stakeholders to translate complex business rules into maintainable solutions; participated in on-call rotation for critical systems.

Skills: Java · Spring Boot · Spring Batch · Oracle SQL · AutoSys

Designed and built custom WordPress websites - implemented UX/content improvements to support conversions.

• Built an AJAX/JavaScript content aggregation tool using web scraping to collect, normalize, and organize relevant content from multiple sources.
• Promoted affiliate offers on social media - planned and executed paid/organic campaigns.
• Managed and optimized Google AdWords campaigns based on performance and conversion data.
• Implemented SEO best practices - keyword research, on-page optimization, content improvements.
• Used Google Analytics to track traffic and behavior, and to drive data-informed optimizations.

Skills: WordPress · JavaScript · AJAX · SEO · Google Analytics · Google AdWords