Paweł is available for hire
Hire PawełPaweł Szydziak
Verified Expert in Engineering
Enterprise Architect and Software Developer
Katowice, Poland
Toptal member since August 12, 2020
Bio
Paweł is a senior software architect and contractor with a decade of experience in enterprise. He works across .NET, distributed systems, and cloud-native architecture, with deep experience in payments at MUFG Investor Services (SWIFT MT, ISO 20022, treasury hubs). Equally comfortable with greenfield architecture and rebuilds of business-critical platforms. Has delivered production systems across banking, fintech, healthtech, travel, real estate, and sports.
Portfolio
On The Beach
.NET, .NET 10, C#, TypeScript, Amazon Web Services (AWS)...
MUFG
C#, .NET, Amazon S3 (AWS S3), Amazon Simple Notification Service (SNS)...
Cryptoways, LLC
Agile, Auth0, React, Next.js, .NET, Entity Framework, GraphQL, PostgreSQL...
Experience
- .NET - 9 years
- C# - 9 years
- SQL - 9 years
- Architecture - 6 years
- GraphQL - 5 years
- Entity Framework - 5 years
- Amazon Web Services (AWS) - 4 years
- React - 3 years
Preferred Environment
Architecture, Object-oriented Programming (OOP), SQL, Docker, Software Architecture, GraphQL, REST APIs, Git, Amazon Web Services (AWS), Solution Architecture
The most amazing...
...work I've designed was a payment system at MUFG that automatically routes payments to SWIFT MT or ISO 20022, depending on what the counterparty supports.
Work Experience
Consultant | Senior Software Engineer & Architect
2026 - 2026
On The Beach
- Led the replacement of a legacy Ruby payment system with a modern multi-PSP payment orchestration platform, with new services continuously added as new payment flows and commercial requirements emerge.
- Designed a PSP-agnostic abstraction layer with Adyen as the first integration, decoupling the platform from any single payment provider.
- Led the introduction of open banking via Tink as a new payment channel, alongside support for additional payment methods, including installments and pay by link.
- Designed an API layer enabling Zendesk AI chatbot integration for natural language payment management.
- Delivered partial production release within the first three months of the contract.
- Leveraged GitHub Copilot as a core development tool throughout the engagement, accelerating delivery.
Technologies: .NET, .NET 10, C#, TypeScript, Amazon Web Services (AWS), Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS), RabbitMQ, Amazon DynamoDB, Entity Framework, Terraform, Kubernetes, Docker, GitHub Copilot, GitLab, GitLab CI/CD, Tink, Open Banking, Zendesk API, Kanban, Adyen Payments, PSD2, Event-driven Architecture, Node.js, Payment Systems, Distributed Systems
Consultant | Senior Back-end Developer and Architect
2022 - 2025
MUFG
- Architected enterprise AWS Lambda serverless infrastructure in .NET, optimizing cold-start performance and establishing organisation-wide standards for scalable serverless architecture.
- Led end-to-end development of dual-protocol cross-border payments platform supporting both legacy SWIFT (MT103 and MT202) and modern ISO 20022 (PACS.008 and PACS.009) standards with multi-tiered authorization workflows.
- Delivered multi-bank treasury hub consolidating in-house and third-party accounts across jurisdictions including Cayman Islands, with real-time monitoring, cross-currency payments, and automated MT940/MT950 reporting.
- Designed an SSI (standard settlement instructions) management system, automating beneficiary onboarding and maintenance for global wealth management clients.
- Supported digital transformation of wealth management operations, centralizing SWIFT payment processing and streamlining transfer agency and fund operations workflows.
- Integrated legacy Flexcube core banking data into modern platforms with full data integrity.
- Built a Hasura GraphQL API ecosystem with advanced caching, query optimization, and horizontal scaling for 24/7 institutional banking operations.
- Established back-end coding standards across distributed teams through code reviews and technical mentoring.
Technologies: C#, .NET, Amazon S3 (AWS S3), Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS), AWS Key Management Service (KMS), Docker, Oracle, PostgreSQL, GraphQL, Hasura, PDFTron, PDF, XLSX File Processing, REST APIs, GitLab, GitLab CI/CD, Amazon Web Services (AWS), Business Services, .NET 8, Azure Kubernetes Service (AKS), AWS Lambda, Jira, AWS Cloud Development Kit (CDK), Single Sign-on (SSO), API Integration, Data Engineering, Scrum, Architecture, Git, Agile, Agile Software Development, C#.NET, Entity Framework, Python, Amazon Cognito, Fintech, Solution Architecture, Data Architecture, Anti-money Laundering (AML), Financial Risk Analysis, Event-driven Architecture, Terraform, Payment Systems, Distributed Systems
CEO | CTO
2022 - 2023
Cryptoways, LLC
- Co-founded a crypto education and live trading platform, holding both CEO and CTO responsibilities, including strategy, fundraising conversations, and hiring.
- Built an end-to-end live marketplace with Binance API integration.
- Negotiated and secured a partnership with TradingView, integrating their advanced graph library to enhance technical analysis tools for users.
- Owned the full development lifecycle, including product, DevOps, back-end, and front-end development.
- Led and mentored the team while staying hands-on with architecture and code.
Technologies: Agile, Auth0, React, Next.js, .NET, Entity Framework, GraphQL, PostgreSQL, Docker, Azure, Azure Blobs, Azure Key Vault, GitHub, Vercel, TradingView, Binance API, Business Services, CTO, Technical Leadership, Fractional CTO, API Integration, Git, C#.NET, Fintech, Solution Architecture, Data Architecture
Developer Lead
2021 - 2022
Alphare.com
- Designed full architecture across web, mobile (iOS and Android), and microservice-based back end, taking the project from inception through MVP delivery.
- Developed a secure and optimized database solution to handle real estate data and protect clients' confidential information.
- Developed a security layer including KYC, AML, and escrow account flows to satisfy US banking standards.
- Integrated Dwolla Wallets to reduce banking fees, alongside Plaid, North Capital, and Auth0.
- Built a shared Lerna module between Next.js web app and the React Native mobile app to eliminate business logic duplication.
- Led the discovery phase, translating client vision into actionable technical stories with accurate MVP estimates across back end, front end, mobile, QA, and DevOps.
- Provided consulting to a non-technical client, helping shape their idea into a viable technical product.
Technologies: Agile, Architecture, Auth0, APIs, Azure, PostgreSQL, React, .NET 6, .NET, React Native, TypeScript, Entity Framework Core, Jest, Plaid API, Dwolla API, React Apollo, Tailwind CSS, Next.js, Sentry, Serilog, JSON Web Tokens (JWT), Azure Notification Hub, Docker, Software Architecture, Technical Leadership, Full-stack Development, Cloud, Leadership, CI/CD Pipelines, Database Design, Databases, ChilliCream GraphQL, Azure Blobs, GraphQL, .NET Core, C#, SQL, Scrum, Git, C#.NET, Visual Studio, Object-oriented Programming (OOP), Entity Framework, Continuous Integration (CI), HTML, Back-end, Microservices, IT Security, Web Development, Web Applications, Serverless, Full-stack, Mapbox, Business Services, Fractional CTO, Jira, API Integration, Agile Software Development, Fintech, Solution Architecture, Data Architecture, Anti-money Laundering (AML), Financial Risk Analysis, Payment Systems
Senior Software Engineer | Performance & Migration Lead
2020 - 2022
Sun Nuclear
- Resolved pessimistic locking and performance issues on SunCHECK, caused by a wrongly implemented database layer, and resolved by replacing Entity Framework with a custom SQL-based implementation.
- Expanded the engagement into a last-resort team responsible for estimating and resolving the most complex cross-technology issues through strong delivery.
- Migrated project of 27,000+ files from .NET Framework to .NET 5, modernizing the entire technology stack.
- Developed a cascading deletion algorithm for records spanning multiple databases, ensuring transactional integrity.
- Set up SSRS on IIS in AWS Windows Server 2019, transitioning database from MySQL to PostgreSQL with multi-tenant architecture.
- Designed AWS Lambda functions in Node.js to automate multi-tenant user creation.
- Introduced CI standards and led the project's transition to a cloud environment.
- Delivered solutions across various technologies with close to no time for adaptation to new environments.
Technologies: C#.NET, Databases, Web Development, .NET 5, Architecture, Microsoft SQL Server, PostgreSQL, SQL, Knockout (Knockout.js), Vue 2, Entity Framework, JavaScript, C#, .NET, Test-driven Development (TDD), Python 3, SQL Server Reporting Services (SSRS), IIS, Windows Server, Amazon S3 (AWS S3), Algorithms, Scripting, Software Architecture, Full-stack Development, Cloud, Leadership, CI/CD Pipelines, REST, Windows Communication Foundation (WCF), SignalR, AWS Lambda, Amazon DynamoDB, Amazon RDS, AWS IAM, Amazon API Gateway, MongoDB, .NET Core, MySQL, REST APIs, Docker, Scrum, Git, Agile, Visual Studio, Object-oriented Programming (OOP), APIs, JSON Web Tokens (JWT), Continuous Integration (CI), Teams, Legacy Code, Performance Optimization, Python, Back-end, Microservices, IT Security, Serilog, Database Design, Web Applications, Serverless, Amazon Web Services (AWS), Full-stack, Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS), Business Services, Azure Kubernetes Service (AKS), Jira, AWS Cloud Development Kit (CDK), Single Sign-on (SSO), API Integration, Data Engineering, Agile Software Development, Amazon Cognito, GitHub, Distributed Systems
Chief Software Architect | Performance Expert
2021 - 2021
Simulation Powered Learning
- Resolved critical performance issues that had blocked the previous team, significantly increasing concurrent user capacity.
- Optimized Entity Framework with pooled DbContext Factory configured for high-efficiency GraphQL data loaders and resolvers.
- Delivered fully functional product, with the work recouping all development costs.
- Led the team through the transition from active development into maintenance with a smooth handover.
- Promoted database maintenance best practices, equipping the team with integration tests to validate their work and prevent future errors.
- Refactored the architecture to reduce coupling between components, ensuring minor code changes no longer triggered chains of failures across unrelated parts of the system.
Technologies: Agile, C#, .NET 5, .NET, React, MySQL, Docker, Auth0, GraphQL, Sentry, Entity Framework Core, Software Architecture, Technical Leadership, Full-stack Development, Cloud, Leadership, CI/CD Pipelines, Azure, React Apollo, ChilliCream GraphQL, .NET Core, Redis, Scrum, Git, C#.NET, Visual Studio, Object-oriented Programming (OOP), APIs, Entity Framework, JSON Web Tokens (JWT), Continuous Integration (CI), Performance Optimization, Back-end, Microservices, IT Security, Serilog, Database Design, Web Applications, Full-stack, Fractional CTO, API Integration, Data Engineering, Agile Software Development, GitHub
.NET Technical Writer
2021 - 2021
Okta
- Created applications demonstrating Okta integration in the Microsoft technology stack.
- Wrote technical guidance on synchronizing Okta solutions within .NET applications.
- Authored an article on SonarQube best practices for clean code without vulnerabilities.
Technologies: Architecture, ASP.NET, .NET, C#, REST APIs, Writing & Editing, Full-stack Development, REST, SonarQube, Git, C#.NET, Visual Studio, Markdown, Full-stack, Technical Writing, Okta, Single Sign-on (SSO), API Integration
Technical Writer with Full-stack Experience
2020 - 2021
Split Software
- Wrote technical articles on feature flag usage across diverse environments, from legacy MVC to modern .NET Core microservices.
- Shared my experience and provided consultation and assistance in the field of .NET SDK.
- Demonstrated experience and flexibility with technology. Provided high-quality technical materials with a large cross-section.
Technologies: C#.NET, Databases, C#, Web Development, Markdown, Back-end, JSON, Microservices, CSS, HTML, .NET, Feature Flags, JavaScript, XAML, REST APIs, Entity Framework, ASP.NET, .NET Core, Node.js, Writing & Editing, Full-stack Development, REST, Git, Visual Studio, Full-stack, Technical Writing, API Integration
Consultant | Software Engineer
2019 - 2021
Avanade
- Developed a provider portal app for a leading Canadian company to be launched on the Canadian, USA, and British markets.
- Delivered the system to manage production for one of the biggest companies in the pharmacy industry. Created a high-performance, load-balanced back end that improved incomes and solved many complex problems.
- Shared knowledge and advice with both business and team members by working as a consultant.
- Worked on big projects from POC and/or MVP till the final version of the software.
- Conducted workshops on creating efficient and performance code (locally), involving the newest featured topics.
- Served as a back-end tech lead on the project with great success. The project ran smoothly without any major issues after its release.
- Helped introduce the new members to the company, mentored them, and advised them on their career path.
Technologies: C#.NET, Databases, Web Development, SQL, Jest, JSON, React, Architecture, Teams, Quartz.NET, Microservices, Back-end, CSS, JavaScript, HTML, XAML, Event Sourcing, Continuous Integration (CI), Entity Framework, Model View ViewModel (MVVM), Azure DevOps, Elasticsearch, Universal Windows Platform (UWP), MongoDB, Redis, ASP.NET, Git, C#, Dapper, GraphQL, RabbitMQ, Docker, .NET, .NET Core, Test-driven Development (TDD), Software Architecture, Technical Leadership, Full-stack Development, Leadership, CI/CD Pipelines, REST, PostgreSQL, REST APIs, Scrum, Agile, Visual Studio, Object-oriented Programming (OOP), APIs, Workflow, JSON Web Tokens (JWT), Redis Queue, Redis Cache, ETL, Performance Optimization, Azure, React Apollo, Serilog, Algorithms, Database Design, Web Applications, Full-stack, Desktop App Development, Jira, API Integration, Data Engineering, Agile Software Development, Solution Architecture, Event-driven Architecture, Distributed Systems
Software Engineer | .NET Developer
2017 - 2019
Stats Perform
- Designed and built an event-sourced architecture where the full state of any match could be reconstructed from its events, with video-time ordering allowing late and out-of-order event ingestion without state corruption.
- Built a data platform sold to commercial clients, including bookmakers and Google feeds, covering live events such as Champions League matches under strict SLA.
- Created WPF applications for real-time sports data collection synchronized with minimal latency across multiple stations operating on the same match.
- Built an MVVM framework from scratch, similar to Caliburn.Micro or Prism, significantly shaping architectural design skills.
- Developed and maintained legacy systems, including the soccer collection client used for live Champions League coverage.
- Implemented complex sports rules and edge cases by reading actual referee guides.
Technologies: IT Security, SQL, JSON, Back-end, XAML, Event Sourcing, Continuous Integration (CI), Architecture, Visual Basic .NET (VB.NET), PostgreSQL, Redis, Agile, REST APIs, Git, Databases, MySQL, C#, C#.NET, ActiveMQ, RabbitMQ, Windows Presentation Foundation (WPF), Windows Forms (WinForms), Docker, VB.NET, .NET, Test-driven Development (TDD), Full-stack Development, Windows Communication Foundation (WCF), Scrum, Visual Studio, Object-oriented Programming (OOP), APIs, Legacy Code, DataGrip, Database Design, Full-stack, Desktop App Development, Jira, Agile Software Development, Event-driven Architecture
Quality Assurance
2016 - 2017
Acaisoft
- Developed and maintained Selenium WebDriver automation tests for Striim, a streaming data platform for enterprise databases.
- Led a team of manual testers, overseeing regression test development.
- Authored comprehensive product documentation for the QA team and end users.
Technologies: Databases, JSON, Selenium, Continuous Integration (CI), Windows, Agile, Scrum, Agile Software Development, SQL, Bash, TestCaseLab, JUnit, Selenium WebDriver, Java, Quality Assurance (QA), CI/CD Pipelines, REST APIs, Git, APIs
Experience
Dual-protocol Payment Messaging Platform: SWIFT MT and ISO 20022 MX Implementation for MUFG
A dual-protocol payment messaging engine implementing both legacy SWIFT Payment Messages (MT103, MT202) and modern ISO 20022 MX (PACS.008 and PACS.009) protocols within a single system. The hybrid architecture enables seamless coexistence during the global SWIFT-to-ISO 20022 transition period and provides enhanced message transmission security through rich, structured global data standards.
The engine offers universal messaging flexibility: regardless of whether counterparties support legacy MT formats or modern ISO 20022 standards, the system automatically selects and formats the appropriate message type. This eliminates partner compatibility constraints and ensures maximum reach across the global financial network.
The platform incorporates sophisticated authorization workflows with multi-level approval processes, supporting complex organizational hierarchies and compliance requirements. Payment initiators create transactions that flow through customizable approval chains with role-based signatory permissions, ensuring proper segregation of duties. The complete authorization lifecycle is tracked with detailed audit trails and real-time monitoring.
The engine offers universal messaging flexibility: regardless of whether counterparties support legacy MT formats or modern ISO 20022 standards, the system automatically selects and formats the appropriate message type. This eliminates partner compatibility constraints and ensures maximum reach across the global financial network.
The platform incorporates sophisticated authorization workflows with multi-level approval processes, supporting complex organizational hierarchies and compliance requirements. Payment initiators create transactions that flow through customizable approval chains with role-based signatory permissions, ensuring proper segregation of duties. The complete authorization lifecycle is tracked with detailed audit trails and real-time monitoring.
Global Wealth Management and Digital Banking Payments Platform for MUFG
A digital banking platform serving as the central transaction processing hub for SWIFT payment messages (MT103 and MT202) in fund administration and investment payments at MUFG Investor Services. Built specifically for global wealth management clients, the platform digitizes and streamlines transfer agency and fund operations workflows that previously required significant manual intervention.
A core capability is comprehensive self-service SSI (standard settlement instructions) construction and authorization, replacing manual onboarding processes with automated workflows. The platform maintains strict adherence to global AML, KYC, and CDD compliance procedures for cross-border transactions.
Implementation of centralized payment processing across previously fragmented operations reduced manual interventions across Transfer Agency workflows and provided real-time transaction monitoring across the wealth management lifecycle. The platform integrates with existing core banking systems while maintaining regulatory compliance across multiple jurisdictions.
A core capability is comprehensive self-service SSI (standard settlement instructions) construction and authorization, replacing manual onboarding processes with automated workflows. The platform maintains strict adherence to global AML, KYC, and CDD compliance procedures for cross-border transactions.
Implementation of centralized payment processing across previously fragmented operations reduced manual interventions across Transfer Agency workflows and provided real-time transaction monitoring across the wealth management lifecycle. The platform integrates with existing core banking systems while maintaining regulatory compliance across multiple jurisdictions.
Open Treasury Hub for MUFG Cayman Bank
A comprehensive treasury management platform designed to enhance MUFG Cayman Bank's service offerings through a globalized open treasury hub. The system enables sophisticated same-currency and cross-currency payment management for Fund Administration across in-house Cayman Island operations and international third-party banks. It features advanced real-time reporting capabilities that utilize the MT940 and MT950 standards for daily transaction activity monitoring.
The platform serves as a robust foundation for expanding Cash Concentration functionality, supporting both Cayman Bank Accounts and third-party bank account management. Implementation includes multi-jurisdictional compliance frameworks, automated statement generation, and real-time settlement monitoring, which significantly improve operational efficiency and client transparency.
The platform serves as a robust foundation for expanding Cash Concentration functionality, supporting both Cayman Bank Accounts and third-party bank account management. Implementation includes multi-jurisdictional compliance frameworks, automated statement generation, and real-time settlement monitoring, which significantly improve operational efficiency and client transparency.
Surface Hub App for Pfizer (via Avanade)
A production management system for one of the world's largest pharmaceutical industry leaders. The application was deployed via Microsoft Surface Hub displays, with a UWP front-end built for the Surface Hub form factor.
The back-end was architected as a high-performance, load-balanced .NET service, with PostgreSQL and Oracle for transactional data persistence, Redis for caching, and Dapper for the data access layer. Node.js was used for database migrations.
The project boosted operational efficiency and resolved complex production management challenges. I contributed as a senior .NET developer, ensuring the project ran smoothly and was released without major issues. I also conducted internal workshops on high-performance coding practices, sharing expertise across the team.
The back-end was architected as a high-performance, load-balanced .NET service, with PostgreSQL and Oracle for transactional data persistence, Redis for caching, and Dapper for the data access layer. Node.js was used for database migrations.
The project boosted operational efficiency and resolved complex production management challenges. I contributed as a senior .NET developer, ensuring the project ran smoothly and was released without major issues. I also conducted internal workshops on high-performance coding practices, sharing expertise across the team.
SunCHECK: Independent Patient and Machine QA Platform for Sun Nuclear
https://www.sunnuclear.com/suncheckSunCHECK is a complex application for integrated, independent patient and machine QA in radiation therapy. Built in Vue with a legacy JavaScript and Knockout.js layer, it consolidates patient and machine QA in a single interface.
I was designed for secure multi-tenant architecture on-premises and in the cloud. New hospitals or hospital networks can be registered in minimal time using serverless computing. The project also covers software for testing specialized radiotherapy devices such as Linear Accelerators, which require daily settings adjustments where patient safety is the highest priority.
I migrated the entire project, comprising 27,000+ files, from .NET Framework to .NET 5, including WCF services for inter-service communication and SignalR for real-time front-end updates. I replaced Entity Framework with a direct SQL data layer and developed a cascading-deletion algorithm across multiple databases to ensure transactional integrity, and set up serverless tenant management in Node.js.
I was designed for secure multi-tenant architecture on-premises and in the cloud. New hospitals or hospital networks can be registered in minimal time using serverless computing. The project also covers software for testing specialized radiotherapy devices such as Linear Accelerators, which require daily settings adjustments where patient safety is the highest priority.
I migrated the entire project, comprising 27,000+ files, from .NET Framework to .NET 5, including WCF services for inter-service communication and SignalR for real-time front-end updates. I replaced Entity Framework with a direct SQL data layer and developed a cascading-deletion algorithm across multiple databases to ensure transactional integrity, and set up serverless tenant management in Node.js.
Payment Orchestration Platform Rebuild for On the Beach
A multi-PSP payment orchestration platform for one of the UK's leading online travel agencies, replacing a legacy Ruby payment system with a modern, distributed architecture. The platform supports a range of payment methods, including card payments, installments, pay-by-link, and open banking via Tink, across multiple payment service providers.
The architecture is built around a PSP-agnostic abstraction layer with Adyen as the first integration, enabling future providers to be onboarded without changes to core platform logic. New services are continuously added as new payment flows and commercial requirements emerge. A dedicated API layer was also prepared to support Zendesk AI chatbot integration, enabling agents and customers to manage payments through a natural language interface.
GitHub Copilot was used throughout development to accelerate delivery.
The architecture is built around a PSP-agnostic abstraction layer with Adyen as the first integration, enabling future providers to be onboarded without changes to core platform logic. New services are continuously added as new payment flows and commercial requirements emerge. A dedicated API layer was also prepared to support Zendesk AI chatbot integration, enabling agents and customers to manage payments through a natural language interface.
GitHub Copilot was used throughout development to accelerate delivery.
Real Estate Securities Platform for Alphare
An MVP web and mobile application providing a highly secure fintech solution for selling real estate shares. To reduce banking fees, a custom solution using Dwolla Wallets was introduced. To satisfy US banking standards, the app implemented KYC, AML, and an escrow account for transaction verification.
Built web and mobile applications that shared a common Lerna module to eliminate business logic duplication. The web app was built with Next.js and React, while the mobile app used React Native, supported by a .NET microservices back end. Communication between the back end and front end was handled through GraphQL, while third-party providers, including Dwolla, Plaid, and North Capital, were integrated into the back end. Auth0 was implemented for authentication and authorization.
As Developer Lead, I significantly influenced the choice of technology stack and selected the right people to fit into the team. I was also responsible for MVP estimation, which proved accurate despite the project's complexity.
Built web and mobile applications that shared a common Lerna module to eliminate business logic duplication. The web app was built with Next.js and React, while the mobile app used React Native, supported by a .NET microservices back end. Communication between the back end and front end was handled through GraphQL, while third-party providers, including Dwolla, Plaid, and North Capital, were integrated into the back end. Auth0 was implemented for authentication and authorization.
As Developer Lead, I significantly influenced the choice of technology stack and selected the right people to fit into the team. I was also responsible for MVP estimation, which proved accurate despite the project's complexity.
Medical Provider Portal for Morneau Shepell (via Avanade)
A web application that manages medical appointment workflows with different flows for various clients and providers.
I was the first person on the project, taking it from POC through MVP to final release. Holding a back-end tech lead position on a large enterprise project that reached production without any major bugs was a significant achievement. I designed the architecture using a then-cutting-edge stack including React, GraphQL, and .NET Core 3.1, which had been released just a week earlier.
I implemented business workflows, set up MongoDB databases, and integrated .NET Core microservices with a GraphQL API back end. I also set up database operations using a code-first approach with Entity Framework Core 3. Redis was used for caching, subscription queues, and message queues because the client was already using it. The entire product was fully Dockerized.
I was the first person on the project, taking it from POC through MVP to final release. Holding a back-end tech lead position on a large enterprise project that reached production without any major bugs was a significant achievement. I designed the architecture using a then-cutting-edge stack including React, GraphQL, and .NET Core 3.1, which had been released just a week earlier.
I implemented business workflows, set up MongoDB databases, and integrated .NET Core microservices with a GraphQL API back end. I also set up database operations using a code-first approach with Entity Framework Core 3. Redis was used for caching, subscription queues, and message queues because the client was already using it. The entire product was fully Dockerized.
Real-time Sports Data and Event Sourcing Platform for Stats Perform
A set of applications used to collect sports data in real time, sold to commercial clients, including bookmakers and Google feeds. Live coverage included Champions League matches under a strict SLA, with financial penalties for breaches.
The platform was built on an event-sourced architecture: the full state of any match could be reconstructed entirely from its events. Event ordering was driven by video timestamps rather than arrival time, allowing late or out-of-order events to be ingested without corrupting state, and enabling clients to query the match at any point in its timeline.
I built an MVVM front-end in WPF and created an MVVM library from scratch, similar to Caliburn.Micro or Prism. I used the .NET Framework as the standard, with C# and VB.NET (mainly VB.NET for legacy projects). For communication between collection stations, ActiveMQ was initially used and later migrated to RabbitMQ.
I worked in an international Scrum team of seven, delivered station synchronization on a tight schedule, and provided data to clients, including bookmakers and aggregators. Performance, event sourcing, and legacy code were core challenges of the role.
The platform was built on an event-sourced architecture: the full state of any match could be reconstructed entirely from its events. Event ordering was driven by video timestamps rather than arrival time, allowing late or out-of-order events to be ingested without corrupting state, and enabling clients to query the match at any point in its timeline.
I built an MVVM front-end in WPF and created an MVVM library from scratch, similar to Caliburn.Micro or Prism. I used the .NET Framework as the standard, with C# and VB.NET (mainly VB.NET for legacy projects). For communication between collection stations, ActiveMQ was initially used and later migrated to RabbitMQ.
I worked in an international Scrum team of seven, delivered station synchronization on a tight schedule, and provided data to clients, including bookmakers and aggregators. Performance, event sourcing, and legacy code were core challenges of the role.
Performance Rescue for Simulation Powered Learning
https://simulationpl.com/• Joined after a previous team failed to fix critical performance issues blocking the platform from scaling.
• Resolved the bottlenecks, significantly increasing concurrent user capacity.
• Optimized Entity Framework with a pooled DbContext Factory configured to work seamlessly with high-efficiency GraphQL data loaders and resolvers.
• Delivered a fully functional product, with the work recouping all development costs.
• Led the team through transition from active development to maintenance, introducing integration tests and best practices that reduced project cohesion and minimized cascading failure risk.
• Resolved the bottlenecks, significantly increasing concurrent user capacity.
• Optimized Entity Framework with a pooled DbContext Factory configured to work seamlessly with high-efficiency GraphQL data loaders and resolvers.
• Delivered a fully functional product, with the work recouping all development costs.
• Led the team through transition from active development to maintenance, introducing integration tests and best practices that reduced project cohesion and minimized cascading failure risk.
Toptal React Academy
The Toptal React Academy is an exclusive learning program that teaches the React framework to select members of the Toptal network. After a month of study, all graduates are tasked with completing a 30-40 hour final project to build and deliver a React app from scratch.
Education
2016 - 2020
Bachelor’s Degree in Informatics Major in Databases
Silesian University of Technology, Faculty of Automatic Control, Electronics, and Computer Science - Gliwice, Poland
Certifications
OCTOBER 2023 - OCTOBER 2026
AWS Certified Solutions Architect – Associate
Amazon Web Services Training and Certification
AUGUST 2023 - AUGUST 2026
AWS Certified Developer - Associate
Amazon Web Services Training and Certification
JULY 2023 - JULY 2026
AWS Certified Cloud Practitioner
Amazon Web Services Training and Certification
DECEMBER 2020 - PRESENT
Toptal React Academy Graduate
Toptal, LLC
Skills
Libraries/APIs
Entity Framework, REST APIs, React, React Redux, React Router, AWS Amplify, Selenium WebDriver, Windows Forms (WinForms), Redis Queue, Vue 2, Node.js, Plaid API, Dwolla API, Serilog, SignalR, Stripe, Stripe API, Binance API, Socket.IO, Zendesk API
Tools
GitHub, Amazon Cognito, Dapper, Git, RabbitMQ, Visual Studio, Auth0, Mongoose, AWS IAM, Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS), AWS Key Management Service (KMS), Azure Kubernetes Service (AKS), Jira, AWS Cloud Development Kit (CDK), n8n, Claude, Terraform, GitHub Copilot, Adyen Payments, ActiveMQ, TestCaseLab, DataGrip, Sentry, React Apollo, SonarQube, Azure Key Vault, PDFTron, GitLab, GitLab CI/CD
Languages
C#.NET, GraphQL, SQL, C#, VB.NET, XAML, JavaScript, TypeScript, Java, Visual Basic .NET (VB.NET), Bash, Python, HTML, CSS, SCSS, Markdown, Python 3, Pug
Frameworks
.NET, .NET Core, .NET 6, Next.js, .NET 8, Windows Presentation Foundation (WPF), ASP.NET, JSON Web Tokens (JWT), Redux, Express.js, Hibernate, JUnit, Selenium, Jest, Knockout (Knockout.js), .NET 5, Entity Framework Core, React Native, Tailwind CSS
Paradigms
Object-oriented Programming (OOP), Model View ViewModel (MVVM), REST, Agile Software Development, Scrum, Continuous Integration (CI), Agile, Microservices, Test-driven Development (TDD), Serverless Architecture, Desktop App Development, Event-driven Architecture, Kanban, Azure DevOps, Event Sourcing, ETL, Database Design
Platforms
AWS Lambda, Amazon Web Services (AWS), Docker, Firebase, Azure, Vercel, AWS Cloud Computing Services, Universal Windows Platform (UWP), Windows, Heroku, Windows Server, Azure Notification Hub, ChilliCream GraphQL, Linux, Kubernetes, Mapbox, Oracle
Storage
PostgreSQL, Amazon S3 (AWS S3), MySQL, MongoDB, Redis, Databases, Redis Cache, JSON, Amazon DynamoDB, Hasura, Elasticsearch, Microsoft SQL Server, SQL Server Reporting Services (SSRS), Azure Blobs
Other
Architecture, Back-end, Writing & Editing, Software Architecture, CTO, API Integration, Fintech, Solution Architecture, Data Architecture, .NET 10, Workflow, APIs, Legacy Code, Feature Flags, Styled-components, Web Development, Algorithms, Technical Leadership, Full-stack Development, Leadership, Quality Assurance (QA), Amazon RDS, Amazon API Gateway, Full-stack, Cloud Computing, Cloud Platforms, Cloud Services, Technical Writing, Business Services, Fractional CTO, Okta, Single Sign-on (SSO), Data Engineering, Agentic AI, Anti-money Laundering (AML), Open Banking, PSD2, Tink, Payment Systems, Distributed Systems, Teams, Quartz.NET, Performance Optimization, Optical Character Recognition (OCR), Tesseract, IT Security, IIS, Scripting, Cloud, CI/CD Pipelines, Windows Communication Foundation (WCF), Web Applications, Serverless, Containers, Axios, Bcrypt, TradingView, PDF, XLSX File Processing, Code Deployment, Networking, Storage, Cloud Infrastructure, Financial Risk Analysis, Vue.Js
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