Legacy Modernization & ERP Architecture
Stabilization, domain boundaries, data ownership and migration of complete business processes.
Piotr Mucha · Principal Software Engineer
Architecture and implementation should not be separated by a handoff.
I connect system architecture, implementation of the hardest parts and responsibility for the production outcome.
I work across ERP, e-commerce, marketing automation, financial integrations, AWS platforms and applied AI. The starting point remains the business process that cannot be stopped.
Principal-level ownership
The architecture decision remains connected to its delivery.
I work directly on architecture, critical implementation paths and production risk. My responsibility does not end with a diagram or a handoff to another team.
When a project needs more delivery capacity, FairyDeck can bring in specialists without diluting my personal responsibility for technical direction and safe production delivery.
Scope of work
The main specialization is ERP and legacy modernization without stopping the business.
Operational Excellence
Reversible delivery, observability, backup, recovery and safe production migrations.
Cloud & Platform Engineering
AWS, infrastructure as code and platforms that support reliable delivery.
Integrations & Data
Explicit contracts, regulated financial integrations, data flows and controlled failure semantics.
E-commerce & Marketplace Systems
Order, support and product-data processes across connected sales systems.
AI-enabled Engineering
Auditable use of agentic tooling with versioning, review, tests and rollback.
Selected work
Different systems, one standard for ownership and evidence.
The case studies separate Piotr’s personal contribution, team delivery, project constraints and production-verified outcomes.
Modernizing a critical ERP without stopping sales, purchasing or warehouse operations.
A multi-channel automotive parts wholesaler relied on several undocumented, tightly coupled legacy systems. Instead of rewriting everything at once, I moved complete business processes into auditable domains while keeping sales, purchasing and warehouse operations online.
Modernizing a marketing automation platform processing up to about 45,000 events per minute.
At roughly 1,000 integrated stores, disk-based event processing and server-by-server scaling were reaching reliability and cost limits. The platform moved to queues and scalable workers while critical PHP and Java components were modernized incrementally.
Normalizing European PSD2 bank integrations for an Account-to-Account platform handling hundreds of thousands of transactions each month.
European banks exposed different APIs, statuses and failure semantics. I implemented integrations that mapped these contracts into one Account-to-Account payment flow with Mutual TLS, certificate handling and explicit behavior for retries, duplicates and ambiguous states.
Removing customer lookup from support calls on an e-commerce platform serving more than 20,000 stores.
Support agents handling roughly 400 calls a day could spend up to 60% of a conversation identifying the caller and reconstructing their context. A telephony integration prepared the customer, store and support history before the call was answered, practically eliminating that lookup step.
Automating catalog updates for nearly 10 million automotive products.
Supplier data was incomplete and inconsistent, while each catalog update required days of developer work. I designed an automated architecture that processes weekly TecAlliance deltas after publication and keeps a standardized catalog of nearly 10 million products current.
FairyDeck · Piotr Mucha
Do you need technical ownership without another management layer?
The first conversation establishes the critical process, the largest risk and whether an assessment, stabilization engagement or ongoing architecture partnership is the right next step.
Discuss your system