I design and build the backend of large e‑commerce platforms. I start from the business process and choose the architecture and integrations so that the system solves the company’s real problems, not just runs.
I also build my own digital products and websites for smaller businesses.
I start from the company’s problem, not from a framework.
The system keeps growing and every change touches several places at once.
I model the process together with the business and split the system into contexts before the first line of code is written.
The store needs features that off‑the‑shelf modules don’t provide.
I develop and optimise large online stores and build modules tailored to the project.
Orders and external systems have to exchange data without manual work.
I connect the platform with external systems through APIs and message queues.
Search and queries slow down as traffic grows.
I speed up search and queries so the store keeps working at peak sales too.
The platform works, but someone has to take care of it every day.
I look after the platform from deployment to day‑to‑day work: I measure, fix and extend.
A small business needs a website with sign‑ups or an app of its own.
Business websites with online enrolment and mobile apps, such as Practice and Kidalu.
Four stages, in this order: from understanding the process to maintaining a running system.
I break the process down into sticky notes: what happens, who decides and where it hurts.
A shared picture of the process: what happens, who decides and where the problems are.
Event Storming
I split the system into contexts so that a change in the cart doesn’t break invoices.
A context map: which parts of the system are responsible for what.
Domain‑Driven Design
PHP, tests and integrations that are still readable a year later.
Modules and integrations ready to deploy and to build on.
PHP · MySQL · RabbitMQ
I measure, optimise and fix. The store has to work at peak sales too.
A platform that stays stable at peak sales as well.
Solr · performance
I treat AI as a pair programmer: it speeds things up, but the decisions stay with me. 10xDevs certificates, one with distinction, and zero belief in magic.
On a B2B contract, as the company CodeDriven. I work from Mikołów, Poland — hybrid or remote.
Yes. Since 2017 I have been developing and maintaining e‑commerce platforms on a B2B basis in cooperation with merce.com.
With a conversation about what should work better. We first break a complex process down into events (Event Storming) and only then plan the code.
Yes: business websites with online enrolment and mobile apps, such as Practice and Kidalu.
From a reporting system on Joomla to the backend of large online stores.
2017 – today
B2B cooperation with merce.com · Mikołów, Poland · hybrid
2016 – 2017
JSJ Group · Gliwice, Poland
PHP application development
2015 – 2016
I-Systems · Gliwice, Poland
HTML e‑mail coding, Allegro auction templates
2013 – 2015
MEDAS Sp. z o.o. · Katowice, Poland
A reporting system based on the Joomla CMS
I have been writing PHP since 2013. I started with a reporting system on Joomla, then came e‑mail templates and Allegro auction templates, and today it is the backend of stores that cannot afford to stop.
I studied computer science and econometrics, so for me the business process is the starting point, not an obstacle. Before I write a module, I want to know what really happens between an order and an invoice.
Sebastian RosińskiPHP developer, e‑commerce backend · Mikołów, Silesia, Poland
Tell me what you want to build or what has stopped working. I’ll come back with a concrete answer, not a template offer.