Paweł Pacana

Worked as part of a tight-knit engineering team with direct CTO reporting, taking ownership of key technical decisions. Enhanced a double-entry bookkeeping system by implementing batch processing, significantly reducing background job execution time and improving system throughput. Designed and and implemented a front-end mapping tool in Elm, allowing accountants to visually define rules for categorizing transactions against their chart of accounts. Architected read-optimized data models to power cashflow statements and financial reports across multiple time granularities (daily, monthly, quarterly), optimizing for low-latency rendering and scalable query performance. Integrated open banking APIs for transaction retrieval, troubleshooting specification gaps and documentation inconsistencies across providers.

Mentored the team on RailsEventStore best practices after they had independently selected and adopted it over competing solutions. Integrated a headless Shopify storefront with third-party logistics and Salesforce document flow. Built an analytics facade to selectively surface data in optimized formats for business intelligence consumption.

Designed a star-schema data warehouse fed by domain events to enable cross-system reporting. Led an incremental, non-disrupting migration of a public API to a more efficient serialization library using sampled production traffic for validation in place of missing test coverage. Applied lessons from high-demand, resource-constrained traffic to design better model boundaries and shorter event streams. Contributed to an in-house event store that helped shape the design of RailsEventStore. Later led its replacement through a zero-downtime online migration, incrementally moving millions of event rows without service interruption. Gained firsthand experience scaling a product across market segments: from independent organizers to managed accounts to enterprise clients—understanding the unique demands of each.

Designed a hierarchical configuration system enabling white-label deployments for multiple publishers. Automated multi-tenant deployments with Terraform, SaltStack, and Chef Solo, improving provisioning consistency and operational efficiency. Engaged directly with customer support to troubleshoot issues, deepen domain expertise and translate feedback into system improvements.

Accelerated deal closures by improving operations workflows and reducing manual bottlenecks. Introduced event-driven process managers to enable instant matching between caterers and customers, improving responsiveness and reducing delays.

Introduced infrastructure-as-code to automate VM provisioning on a pool of private, dedicated servers. Partnered with mobile developers to design and integrate in-app purchase APIs, enabling seamless transaction flows across platforms.

Responsible for development of an e-learning platform for high-school students and improving internal CMS product with Ruby on Rails.

My project was to research and implement new data backend based on distributed version control system (Mercurial) for the MoinMoin Wiki. I worked with Radomir Dopieralski as my project mentor.

Responsible for web application architecture design and development using ASP.NET 2.0 and ASP.NET AJAX. Delivered a new e-commerce frontend featuring WYSIWYG configuration, integrated with the company's flagship ERP platform.

Responsible for preparing and improving Windows and Linux installations on lab workstations, at scale. Maintaining and keeping up-to-date directory services — for students and teachers of the faculty. Ensuring software and hardware reliability, improving and monitoring system and network security.