Szymon Mrozek

B2B mobile application for fleet customers of a global fuel retailer, supporting electric vehicles charging, payments, station discovery, and operational company account management.

The primary challenge was embedding a complete standalone iOS application into the main app under an extremely compressed timeline.

This required integrating a large codebase without duplicating dependencies, adapting the modular structure of the embedded app to fit the host application’s architecture, and ensuring the resulting solution remained reviewable, maintainable, and production-ready despite the scale and speed of the integration.

Heads were responsible for their functional areas and the outcomes delivered within them. They set priorities, defined standards, and made decisions affecting multiple teams. Heads coordinated across functions to keep direction and execution aligned. They represented their areas in leadership discussions and decision forums. Their role combined strategic ownership with accountability for results.

This role moved the focus from operational leadership into strategic ownership, with challenges centered around questioning and shaping the company’s service strategy rather than simply executing it.

Operationally, the role involved leading a layer of mid-level managers responsible for the entire service delivery branch of the organization. Key challenges included standardizing the service offering end-to-end—from a clear definition of what the service actually is, through explicit expectations around outcomes, quality, and accountability—where previously much of this had been implicit or inconsistent. A critical area of responsibility was designing and implementing a reliable financial management and planning system for service delivery. Historically, the organization struggled with a significant gap between financial predictions and actual results, leading to poor decision-making; addressing this gap resulted in meaningful cost savings and a positive financial outcome by year-end, following two consecutive years of losses.

An additional, full-fledged responsibility was ownership of the sales funnel from a delivery perspective, including preparing estimates, materials, and demos that supported sales efforts in a way that was both technically credible and conversion-oriented. The role also involved navigating the organization’s approach to AI in 2025—actively exploring practical, value-driven applications while resisting pressure to adopt AI “at any cost” without clear business justification.

Concrete outcomes delivered by the team included standardization of evaluation processes, rate changes, compensation bands, and cross-department collaboration practices.

On a human level, the team outcomes are: noticeable improvement in trust and working relationships between delivery teams and service leadership, clearer support structures for leaders, and better alignment between individual career paths and the actual work people were doing—within clearly defined business constraints rather than unchecked autonomy.

OpEx was an operational team combining service delivery, client management, and people-related responsibilities. It coordinated day-to-day execution across projects, clients, and teams to keep the business running. OpEx handled escalations, staffing decisions, workload balancing, and client communication. It operated close to the ground, often compensating for unclear ownership or missing standards. In practice, OpEx carried significant responsibility without full strategic authority.

This role began in an environment with no clear, operational definition of what “good leadership” actually meant in a service-based organization.

Team leaders were largely operating on high-level visions and personal intuition, with little shared standard for delivery quality, leadership effectiveness, career progression, or compensation frameworks for developers.

A major challenge was navigating deeply rooted, collaboration-specific legacy—each team and client engagement had evolved its own ways of working over the years, often inconsistent and difficult to scale or compare.

As an early step into mid-level management, the work focused on bringing structure where none existed: defining baseline expectations for team leaders, introducing clearer feedback loops, addressing long-standing performance issues, and initiating conversations around career paths, rate bands, and leadership accountability.

Not all initiatives succeeded fully, but most of the core problems were at least surfaced and addressed for the first time.

The role required handling a significant number of difficult conversations, including providing long-overdue feedback and making hard decisions such as letting go of leaders who were no longer effective in their roles, while gradually shifting the organization away from implicit, legacy-driven leadership toward more explicit and actionable standards.

End-to-end encrypted communication platform for enterprise and security-conscious users, combining messaging, voice, and video with strong offline support requirements.

The engagement focused on unblocking a struggling iOS team by addressing both technical and delivery-level issues beyond standard task-based workflows.

Major technical challenges included reducing excessive architectural coupling caused by poorly chosen offline-first patterns, stabilizing a largely undocumented legacy CI system with 45–60 minute build times and flaky tests lacking observability, and restoring team ownership by exposing systemic problems and engaging engineers in solving cross-cutting platform issues rather than isolated Jira tasks.

The dominant e-commerce marketplace in Poland, operating at national infrastructure scale and serving millions of users daily across a highly modularized mobile application.

The main challenge was delivering a large, business-critical C2C selling feature (an undisclosed C2C app) into an existing super-app developed by dozens of engineers, while operating as an external contractor.

This required isolating ownership boundaries without breaking deep integration, designing a highly dynamic selling form varying across categories, delivery methods, and sales models, and actively supporting the early stages of app modularization in a codebase that was only beginning its transition toward a multi-module architecture (currently 230+ modules).

High-traffic local C2C marketplace built under extreme time pressure, driven by a hard marketing deadline tied to a national TV campaign and a broad product scope covering the full mobile e-commerce experience.

Key challenges included delivering the application end-to-end in roughly five months (pre-AI tooling era), coordinating multiple stakeholders with conflicting priorities, and compensating for limited backend availability during active development.

From a technical perspective, this was my first large-scale, properly modularized mobile architecture built from scratch, designed to enable rapid development, easy component replacement (including temporary WebView-based solutions), and long-term scalability, supported by aggressive acceleration techniques such as code generation, one-click module creation, and workflow orchestration optimized for development speed.

Enterprise-scale hospitality application forming a core part of the guest experience for one of the largest resort and entertainment operators in the US, including reservations, loyalty, and on-site services such as mobile room keys.

The project inherited a heavily constrained legacy codebase built around a highly non-standard architecture and a custom internal DSL, resulting in steep onboarding costs and critical production issues, particularly around physical door lock interactions.

Key challenges included executing a deep refactor to reduce architectural complexity, restoring reliability of core guest flows, and building an automated functional test foundation providing sanity coverage for the most critical user journeys, which significantly reduced the cost and risk of regression testing. All of this was delivered while integrating with outdated hotel reservation systems and validating fixes through real-world, on-site testing in Las Vegas properties.

Mobile tools used globally by professional fitness instructors as the primary way to manage and play licensed training music during live classes.

The core technical challenge was building an advanced, low-latency audio engine on iOS, capable of parallel sample playback, multi-track mixing, dynamic tempo changes, and real-time BPM calculation.

The system had to behave deterministically under live conditions, support seamless transitions between tracks, and remain stable across a wide range of devices (including TVs), effectively treating iOS audio processing as a real-time system rather than a typical media player.

Software development services company delivering team augmentation and end-to-end delivery teams across multiple mobile and backend technologies.

The technical challenges extended beyond single-project development and focused on building internal platform capabilities leveraged across many teams and client projects.

This included designing and implementing an end-to-end platform for bootstrapping, provisioning, and managing virtual machines for iOS, Android, and Flutter development, enabling repeatable and scalable development environments.

A significant part of the work revolved around improving developer experience around iOS build infrastructure, including custom-built dependency caching tools, systematic build-time optimizations across all iOS projects, and improvements to CI observability through better monitoring and notification within running and of the completed pipelines.

The role also involved solving complex build-system issues related to compilation, architecture, and linking, automating cross-team code review processes, and contributing to the long-term evolution of the internal iOS platform through developer enablement, creating guidelines, project templates, technical documentation, and running workshops to raise the overall maturity of iOS development across the organization.