Marek Stasikowski

Building AI-powered developer tooling and MCP-based automation systems, focusing on practical applications that deliver measurable productivity gains.

• comms-mcp: A unified communications assistant connecting email, iMessages, and WhatsApp via Model Context Protocol. Processes 280 emails/week with AI summaries, reducing triage time by 70%^[1]. Used to resolve a small claims dispute: instant message retrieval, evidence organisation, and automated court correspondence recovered £1,080.
• hybrid-memory: A semantic memory system combining pgvector embeddings with BM25 full-text search via Reciprocal Rank Fusion, enabling long-running agentic sessions to share insights across projects.

Staff engineer at an omnichannel retail platform, focusing on system resilience, performance optimisation, and developer productivity.

• Unblocked $6M ARR product add-ons feature by pragmatically isolating one component from a stalled "big rewrite", using characterisation tests to safely lift it to production - cutting delivery time from months to 2 weeks.
• Designed circuit breaker patterns for both synchronous (HTTP) and asynchronous (message queue) flows to prevent incidents caused by third-party systems, each costing up to 5 hours of on-call time plus week-long follow-ups.
• Led BFCM load testing and optimisation: tuned Kubernetes HPA, scaled AWS databases, optimised SQL queries - achieving target of 44 orders/second (over 2x previous year's average).
• Prototyped NewStore MCP - connectors to GitLab, AWS, OpenSearch, Prometheus, RabbitMQ, and Kubernetes - reducing incident investigation from up to a day to 20 minutes^[2] by unifying data scattered across microservices, Slack, Confluence, and observability tools.
• Presented at weekly knowledge sharing sessions on legacy codebase strategies, testing approaches, and Monte Carlo-based delivery forecasting.

Marks & Spencer

October 2024 - February 2025

Platform engineer for an 800-engineer monorepo, focused on CI performance and onboarding efficiency.

• Championed Blacksmith migration to halve 30+ minute merge queues and reduce CI costs 4x - design approved, taken over by security review and procurement.
• Quantified onboarding friction: 30 days to get "hello world" to production. First automation iteration estimated to save 5 days per new project.
• Coached teams in mutation testing using Stryker to expose gaps and overlaps in test coverage, providing this as a new platform capability.

Joined as consultant to streamline a 100k+ SLOC React/Redux onboarding application; permanently hired as Principal Engineer after one year.

• Shaped architecture of multi-dimensional onboarding app, clearing significant tech debt while championing TDD, BDD (Cypress, Cucumber), and robust CI/CD practices.
• Led migration from legacy Java monolith to serverless AWS using facade pattern, gradually replacing legacy flows with Lambda functions and Step Functions.
• Designed system integration with SingPass and KYC providers like Signicat.
• Implemented Options trading extensions in the user account section, contributing to multi-million ARR feature rollout within 3 months.
• Zero missed FCA regulatory deadlines - critical for a financial services platform.
• Frequent mentorship unblocking team members across frontend and backend work.

Built customer-facing platform configuration and admin tooling; promoted to Team Lead December 2021.

• Established XP feedback loops: fast tests, acceptance tests, pair programming, daily deploys with QA/PO involvement, and fortnightly stakeholder product reviews.
• Reduced cycle time variability from 50% to near zero - tickets consistently completed in 2 days.
• Replaced finger-in-air estimates with Monte Carlo projections based on historical data, removing time pressure from engineers.
• Reduced time spent on ceremonies: standups under 10 minutes using ActionableAgile aging WIP view, focusing only on outliers and current technical decisions.
• Coached team in TDD; organised practice sessions across London engineering community.

Pret a Manger

January 2020 - April 2020

First engineer on re-platforming effort to end £500k/year agency dependency.

• Designed and gained stakeholder approval for headless CMS architecture (Contentful + Commercetools) with hybrid static/SSR on GCP Cloud Run.
• Laid technical foundation across platform, product, and design: component library with Storybook, establishing protocol with UX/design team.

Engineer for an espionage museum's interactive experiences and visitor profile system in New York.

• Extended games and online profiles with new ways of browsing takeaway videos and exploring visitor data.
• Worked with real-time data streaming from physical devices (RFID wristbands, iPads) throughout the venue via AWS Kinesis.

JavaScript consultant at major UK retailer and Swedish fintech.

John Lewis & Partners

August 2018 - July 2019

• Built foundation for customer support app targeting reduction of £800k/year live agent costs; mentored JL Partners in frontend development.
• Cleared CSS theming tech debt to enable rebranding in My Account. Later built Auth0 integration replacing legacy system.

Klarna

April 2018 - July 2018

Joined Authentication & Personalisation team to take ownership of services inherited from another team, reverse engineering and providing out-of-hours support.

Rebuilt legacy Rails energy switching journey using React/Node with Strangler Fig pattern.

• Improved conversion rate from 2-3% to nearly 4% through modernised UX and A/B tested incremental migration.
• Redirected traffic step-by-step to new stack, eventually reducing Rails app to pure data service.

R&D role pioneering server-side React rendering for checkout pages.

• Established universal React approach that became industry standard; set technical strategy for the business.
• Shared learnings at meetups (NOTHS, Pivotal, University of London) and ReactJS Day Verona.