Marcin Marciszewski
Full-stack developer. Warsaw, Poland. Remote, UK and EU hours.
Web apps, APIs and marketing sites for clients in the UK and EU. Python and TypeScript, end to end.
Selected work
five projects, all live
- 01
Leafline
Demo, 2026
Marketing site for a fast-casual salad chain: menu, locations, catering, mission.
- Next.js 16
- React 19
- TypeScript
- Tailwind CSS 4
- 02
Wilson Landscape
Demo, 2026
Six-page site for a garden design studio, ported from WordPress to Next.js.
- Next.js 16
- TypeScript
- CSS custom properties
- 03
Tideline
Demo, 2026
Single-page site for a London tech recruiter with two enquiry flows.
- Next.js 16
- Tailwind CSS 4
- TypeScript
- 04
Touchmark
Product, 2026
Contact-data validation API with a dashboard, built and run as a real product.
- Python
- FastAPI
- PostgreSQL
- React
- 05
Saltgrass
Demo, 2026
Skincare storefront with filters, product pages, a cart and a mock checkout.
- Next.js 16
- React 19
- TypeScript
- Tailwind CSS 4
Services
Scoped, tested, deployed
- 01
Web applications
Dashboards, portals and internal tools. Next.js or Vue in front, Python or PHP behind, Postgres underneath.
- 02
APIs and integrations
REST APIs, third-party integrations such as payments, CRMs and research databases, background jobs and serverless functions on AWS.
- 03
Marketing sites and landing pages
Fast, accessible and static where possible. Designed to be read, built to be measured.
- 04
AI integrations
MCP servers, retrieval over your own documents, LLM tool calling with guardrails. Scoped, tested, deployable.
About
Writing software since 2019
I build web products end to end: the database and the API, the interface people use, and the pipeline that ships it.
I have written software professionally since 2019, in the UK and in Poland: Python and FastAPI at Welltech, Symfony on VeloBank’s banking systems, Vue and PHP on researchfish.com for Interfolio, and a run of full-stack sites for UK organisations. Before that, a decade in logistics and running my own transport business in London.
Lately that includes AI plumbing: MCP servers that expose internal tools to assistants, retrieval over pgvector, and LLM tool calling that behaves in production.
Experience
2023 to now
Python Developer
Welltech, Remote
FastAPI services, AWS serverless, Postgres. Built MCP servers, a pgvector retrieval system and LLM tool-calling pipelines; integrated the Decagon support assistant.
2022 to 2023
PHP Developer
Bluesoft, for VeloBank, Warsaw
Internal banking systems in Symfony with domain-driven design. Shipped the flow that opens a company and its business account in one go.
2021 to 2022
Full Stack Developer
Interfolio UK, Cambridge
Rebuilt the researchfish.com dashboard in Vue, integrated PubMed, Scopus and ORCID, migrated legacy Drupal features.
2019 to 2021
Full Stack Developer
Lightflows, Guildford
End-to-end sites for UK organisations in Laravel, Drupal, WordPress and React.
- Education
- Software Development Diploma, Code Institute, Dublin. 2018 to 2019
- BSc Logistics, University of Social Sciences, Warsaw. 2007 to 2010
- Languages
- Polish (native), English (C1)
Stack
What the work is built with
- Backend
- Python
- FastAPI
- PHP
- Symfony
- Laravel
- Node.js
- Frontend
- TypeScript
- React
- Next.js
- Vue
- Tailwind CSS
- Data
- PostgreSQL
- pgvector
- MySQL
- MongoDB
- Ops
- Docker
- GitHub Actions
- Traefik
- AWS
- Linux
- AI
- MCP servers
- RAG
- LLM tool calling
- LLM APIs
Contact
Replies within one working day
Tell me what you are building.