Mateusz Bagiński | Dev & Stuff

👋 About me

Hi, I'm Mati. 🐱 My cat says I'm good at debugging, but only when the bug involves opening his treat jar. With 10 years of experience, I've mastered the fine art of pretending I know what I'm doing while wrangling code and occasionally mowing the lawn. I've worked with various clients from startups to large corporations.

⭐ Client Testimonials

"As his primary food source evaluator, I must say his performance is barely acceptable. Yes, he consistently provides sustenance, but yesterday? ONE MINUTE LATE with my dinner. ONE. WHOLE. MINUTE. Simply unacceptable. However, he does open treat jars with remarkable efficiency."

Mr. Dżony

Chief Food Bowl Inspector

💼 Experience (10+ years)

Yearly capacity distribution across projects

	0%25%50%75%100%
2025	CKSource Senior Fullstack Engineer Part-time Dashhub Onliwood
2024	CKSource Senior Fullstack Engineer Part-time Dashhub Onliwood
2023	Bright IT DevOpts / Senior Fullstack Engineer Bytamic / Liiva Senior Frontend Developer Part-time Onliwood Hoqus Productz.com Answear.com
2022	Bright IT DevOpts / Senior Fullstack Engineer Bytamic / Liiva Senior Frontend Developer Silky Coders Senior Fullstack Web Developer Part-time Onliwood Hoqus Productz.com Answear.com Couporando.pl
2021	Silky Coders Senior Fullstack Web Developer Interia.pl RoR / Full Stack Engineer Part-time Onliwood Productz.com Couporando.pl
2020	Interia.pl RoR / Full Stack Engineer Part-time Productz.com Couporando.pl
2019	Interia.pl RoR / Full Stack Engineer Part-time MyBudapester
2018	Interia.pl RoR / Full Stack Engineer
2017	Interia.pl RoR / Full Stack Engineer
2016	Interia.pl RoR / Full Stack Engineer Part-time Quantitative Engineering Design Umwerk
2015	Part-time Quantitative Engineering Design

🕹️ Projects

upolujksiazke.pl

Open-source book review aggregator using React, Nest.JS and Elasticsearch for fuzzy logic book matching with collaborative filtering and bot integration.

TypeScript React NestJS Elasticsearch Node.js

Commercial

Interreg Survey

Survey application for Interreg project with custom form builder, multi-language support and advanced reporting features using Elasticsearch to dynamically generate reports and aggregations.

TypeScript React Marble.js Elasticsearch Node.js

CKEditor 5 Rails

CKEditor 5 Ruby gem - seamless integration with Rails through web components and helper methods. Supports both GPL and commercial licenses with flexible CDN options and translations.

Ruby Rails CKEditor Propshaft Assets pipeline

C Compiler in TypeScript

Multipass portable C lang compiler toolkit with IR code generator including backend, frontend and optimizer phases. Designed to simple prototyping 16bit toy operating systems and games.

TypeScript C Node.js

under-control

Lightweight form control library for React that treats all forms and inputs as recursive composable controls. Alternative to react-hook-form, formik, react-ts-form with focus on component controllability.

TypeScript React

Podman Quadlet Ansible ARM Boilerplate

Example of standalone application deployment to Hetzner Cloud using Rootless podman quadlet systemd services. Compatible with RaspberryPI, costs under $5/month.

Ansible Linux Docker Podman

Librus-API

Open source HTTP client for parsing HTML responses from the Librus/Synergia electronic journal server. Unofficial integration package.

Node.js TypeScript

Micro-racing

Multiplayer 3D isometric racing game developed with WebGL 2.x and neural networks integration.

TypeScript WebGL Node.js

🌟 Experience & Roles What I did in tech?

Full-time

Senior Fullstack Engineer

CKSource

Feb 2024 - Present

Full-time

Contributing to CKEditor 5, one of the most popular open-source text editor in the world.

Resolved critical issues for high-profile clients including CNN, Disney, Volvo, Microsoft, Siemens, UNICEF, Epic, and AT&T
Enhanced accessibility by addressing A11y WCAG issues for government clients such as the Australian and UK Governments
Implemented SoC 2 security patches to ensure robust security compliance
Developed and enforced ESLint rules, integrating custom TS-Morph analysis into the CI build process
Maintained and improved CKEditor integrations for React, Angular, and Vue, including refactoring initialization mechanisms and resolving race conditions
Actively contributed to open-source projects and engaged with the community
Integrated AI capabilities into the editor
Extended the core diffing algorithm of the Operational Transformation framework
Enhanced clipboard support for tables
Implemented search-as-you-type functionality
Developed reusable UI components, such as dropdowns, for various integrations
Improved the editor model AST copy & paste functionality
Upgraded accessibility features, ensuring WCAG VPAT compliance across major parts of the editor

TypeScript React Angular Vue ESLint A11y WCAG CKEditor

Part-time

Senior Fullstack Engineer

Dashhub

Aug 2024 - Present

Part-time

Creating AI search engine powered by Elasticsearch kNN cosine vector similarity comparisons, embeddings analyze, contexual augmentation.

Created RAG AI search engine powered by Elasticsearch kNN cosine vector similarity comparisons, embeddings analyze, contexual augmentation
Developed a Red Hat Enterprise Linux compatible infrastructure using AlmaLinux 9, automatically configured with Ansible and Pulumi, and hosted on Hetzner Cloud with Cloudflare integration.
Ensured high security standards by enforcing strict SELinux policies for containerized environments, implementing robust Nftables firewall configurations, and automating system upgrades. Utilized a rootless Podman setup with systemd-proxyd for filesystem protection.
Configure fail2ban ruleset to automatic ban suspicious traffic.
Set up and configured essential services including Elasticsearch, MinIO, PostgreSQL, NGINX, SystemD, and Podman Quadlet.
Implemented a rapid deployment and rollback solution (under 1 minute) for a monorepo of applications.
Developed backend, frontend, and API applications in TypeScript, following a hexagonal architecture pattern, utilizing Tsyringe for dependency injection, Kysely for database interactions, and React for the frontend.
Directus self-hosted CMS installation and Astro integration.

TypeScript Elasticsearch React AlmaLinux Ansible Pulumi SELinux Podman PostgreSQL MinIO NGINX SystemD Astro

Part-time

DevOpts / Senior Fullstack Engineer

Onliwood

Jan 2021 - Present

Part-time

Create site management dashboard, Hetzner / OVH infrastructure and frontend application storyblok CMS integration.

Implemented infrastructure and achieved sub-1-minute deployment for Dockerized Java and Node applications
Managed cloud infrastructure on OVH and Hetzner using Podman Quadlet and Linux
Developed a single-page application for wood selling using React, Ramda, TypeScript, NestJS, Node, and TypeORM
Worked on government projects related to environmental protection (Główny Inspektorat Ochrony Środowiska)
Created and integrated Docker mono-repo app deployments with GitHub CI
Performed DevOps tasks including Dockerizing applications, creating end-to-end tests, and setting up UAT environments
Managed RabbitMQ and firewalls using nftables
Set up dynamic deployments on staging environments using Docker Swarm, Ansible, Traefik, and GitHub pipelines in OVH cloud
Integrated Storyblok CMS with live-preview in a legacy codebase
Handled recovery and rollback tasks

TypeScript React Node.js NestJS Docker Podman RabbitMQ Ansible Traefik

Full-time

Senior Frontend Developer

Bytamic / Liiva

Apr 2022 - Dec 2023

Full-time

Cooperation with Liiva and Bytamic in selling houses site maintenance.

React / Next.JS / SCSS
CMS Contentful integration
Automatic generate sitemap based on CMS Contentful modifications
Jest / Cypress E2E testing

React Next.js SCSS Jest Cypress Contentful

Part-time

Senior Frontend Developer

Answear.com

Sep 2022 - Nov 2023

Part-time

Refactor internal SSR rendring mechanism, speeding up products grid loading

Part-time task to help with speeding up the site and SEO optimizations using React, Jest, Node, and Redis
Introduced lazy hydration integrated with the SPA application
Implemented a new approach to perform async SSR with support for Redis, IndexedDB, and memory cache
Conducted Lighthouse SEO optimizations
Boosted overall site performance

React Node.js Redis SSR Jest

Part-time

Senior Frontend Developer

Hoqus

Nov 2022 - Sep 2023

Part-time

Mostly part-time job with improving site code quality

TypeScript React

Part-time

Ruby on Rails / Fullstack developer

Productz.com

Jul 2020 - Aug 2023

Part-time

Refactor major parts of productz.com, create SPA internal website management panel.

Node.JS / Ruby on Rails
React / Vanilla.js
Elasticsearch / Postgres / Redis
CDK / ECS / EC2 management
GTM / GA4 / Universal Tracker
Managed AWS EC2 and Cloudflare

Ruby on Rails Node.js React Elasticsearch PostgreSQL Redis AWS

Full-time

DevOpts / Senior Fullstack Engineer

Bright IT

Sep 2022 - Feb 2023

Full-time

Create many projects for company clients and manage their own products.

Lead project coordination and development
Designed backend, frontend, and infrastructure architecture for new projects (mostly hexagonal, serverless - AWS Lambda)
Designed and implemented monadic functional backend modules using a ZIO-like approach with fp-ts, io-ts, and kysely
Implemented Contentful, JIRA, Storyblok, Sendgrid, Brevo, Piwik, and ActiveCampaign backend/frontend CMS integrations
Set up deployments and infrastructure in AWS CDK, ECS, EC2, Lambda, Cognito, CloudFront, S3, VPC, Route53
Set up CI and infrastructure for Ansible, Vagrant, Podman Quadlet, SystemD, MicroOS, and Linux projects
Configured nftables firewall and Linux on simple Debian 12 servers
Set up and implemented an aggregated search engine using AWS OpenSearch/Elasticsearch
Created zero-downtime reindexing for Elasticsearch engine with facets aggregation system
Developed dynamic aggregations fuzzy search conditions builder using AST approach
Designed architecture and implemented new CMS systems
Integrated Turbo Monorepo, D3, Playwright, React, Jest, Next.js, Nest.js, Marble.js, and GraphQL
Conducted E2E testing with Playwright and Jest
Created and optimized Podman/Docker and GitHub CI
Worked with GA4, GTM, and Piwik under ISO27001 jurisdiction

TypeScript AWS Lambda React Next.js Nest.js GraphQL Elasticsearch Docker Podman Ansible

Part-time

PHP / Frontend Engineer

Couporando.pl

Jan 2020 - Dec 2022

Part-time

Part-time support of couporando.pl site, creating kodyrabatowe.interia.pl and kupimytwojanieruchomosc.pl apps.

Creating kupimytwojanieruchomosc.pl SPA app, its api and internal panel using Dockerized Node.JS container + NestJS / React / Ramda / TypeORM
Rewrite whole kodyrabatowe.interia.pl front, small backend changes (PHP, SCSS, JS, JQuery)
Maintain biggest coupons websites in Poland:
- kodyrabatowe.interia.pl
- promocje.smaker.pl
- couporando.pl
Implement PHP/CSS/JS page partials in legacy code, tracking implementation and fixes

PHP React Node.js NestJS TypeORM Docker jQuery

Full-time

Senior Fullstack Web Developer

Silky Coders

Jul 2021 - Mar 2022

Full-time

Customer Experience Team Leader. Maintain websites of the largest clothes shops in Poland.

Created an advanced multi-step return/complaint product creator, used by millions of users across all LPP markets
Conducted meticulous unit testing of all created components
Integrated React components with Magento
Developed an internal content management system
Implemented a fuzzy campaign product targeting system for major brands in Poland (Reserved, House, Mohito, Cropp)

React Magento Unit Testing

Full-time

RoR / Full Stack Engineer

Interia.pl

Apr 2016 - May 2021

Full-time

Lead frontend development of Interia Adretail applications.

Created and maintained Interia.pl layout partials
Developed and maintained JS components on major e-paper websites in Poland such as Promocyjni, Okazjum, Promoceny, Ding, Adretail, and widgets on Interia.pl
Created and maintained internal Interia.pl web panels
Implemented Adserver integrations (Prebid, Criteo, Google Ads, Adocean), including ad creation and tracking
Integrated reusable React components on third-party websites using Adserver
Created a reusable Leaflet reader component
Developed SPA polymorphic microservice-based apps with Redis and GraphQL integration
Conducted SEO optimizations, including creating an automated sitemap generation system
Implemented a fast GraphQL cached client with batching, client cache, and Redis support
Created a fast external React partial prerendering system to introduce SEO-optimized components on several websites
Performed Lerna/monorepo app optimizations
Used Node.js, React, Redux, CoffeeScript, GraphQL (Apollo), Angular, ES6/7/8
Worked with Google Tag Manager, GPT, Gulp/Webpack, Adocean, JSS
Applied Functional Programming using Ramda, Ramda Fantasy, RX, and Rails

Ruby on Rails React Redux GraphQL Redis Angular Node.js SEO

Part-time

Fullstack Node.JS/React Developer

MyBudapester

Feb 2019 - Oct 2019

Part-time

Working for MyBudapester.com, the premium shoe shop in Germany.

Working for MyBudapester.com, the premium shoe shop in Germany.
Fixing and maintance mailing templates.
Create magento mangement panel for internal use.

Node.js React Magento PHP ECommerce

Part-time

Fullstack Python Developer

Quantitative Engineering Design

Nov 2015 - Dec 2016

Part-time

Programming backend and frontend using ES6, JavaScript 1.7, Python Django and Vue.JS.

Working on improving the Africa Soils project, a web application for soil analysis in Africa
Making drone data analysis tools for agriculture
Programming backend and frontend using ES6, JavaScript 1.7, Python Django and Vue.JS.

Python Django Vue.js Angular jQuery

Part-time

Frontend Developer

Umwerk

Oct 2016 - Dec 2016

Part-time

Creating simple BMW presentation for self driving car - Angular 1.x with IE 10 support.

Maintain Guidebase.com in Angular 1.x, JQuery.
Creating simple BMW presentation for self driving car - Angular 1.x with IE 10 support.

Angular jQuery