Josef Swaczyna — Swaczyna Software

I build systems you can rely on.

Freelance senior Java engineer and tech lead with 10+ years of experience across banking, trading platforms and data-heavy products. Currently leading data engineering and AI integration for Codexis at Atlas Group.

Now: Tech Lead — Codexis data, Atlas Group
Get in touch My experience
10+ years of professional development
2 global banks among clients
Java 25 current production stack
C1 English proficiency

@Services

What I can do for you

Backend & architecture

Modern Java backends designed to last — Spring Boot microservices, event-driven systems with Kafka, clean APIs and delivery pipelines that ship.

Data platforms

High-volume data acquisition, transformation and delivery — PostgreSQL, Redis and streaming pipelines that keep products fed with reliable data.

AI integration

AI in the product and in the process. I design LLM-powered features and AI-first development workflows that actually make it to production.

Tech leadership

I lead teams, own architecture decisions and run code reviews that teach. Juniors I mentor grow into seniors.

@Experience(since = 2012)

From PHP webs to AI-first platforms

  1. 2024 — now current

    Tech Lead — Codexis data

    Atlas Group

    Leading the data platform behind Codexis: data acquisition, transformation and AI integration on a modern architecture. Owning architecture decisions and growing a team of developers at an AI-first company.

    Java 25 · Spring Boot 4 · Kafka · Redis · PostgreSQL · Testcontainers · AI/LLM

  2. 2023 — 2024

    Senior Application Developer

    Barclays

    Greenfield internal financial platform. Owned architecture, planning and the full integration and delivery process, developing both backend and frontend.

    Java 17 · Solace · Spring WebFlux · Angular · Oracle

  3. 2021 — 2023

    Senior Application Developer

    EPAM Systems

    Trading platform for a major international bank — AWS microservices with Kafka and FIX protocol integrations, parallel data-parsing pipelines, code reviews and mentoring.

    Java 17 · AWS · Kafka · Kubernetes · Spring Boot · React

  4. 2017 — 2020

    Senior Application Developer

    Tieto

    Led a team of three building an invoicing system for the Finnish public sector; oversaw a company-wide Java 6 → 8 migration of shared components.

    Java · Spring · Angular · PostgreSQL · IBM DB2

  5. 2015 — 2016

    Application Developer

    IDC CEMA

    Internal tools keeping the company running — product and contract management, employee records and central authentication.

    Java · Spring · AngularJS · Oracle · Lucene

  6. 2012 — 2015

    Web Developer

    Digito.cz

    Where it started: custom PHP webs and e-commerce, including a custom Bitcoin payment gateway back when that was exotic.

    PHP · JavaScript · WordPress · OpenCart

@TechStack

Tools I reach for

Core Java

  • Java 17–25
  • Spring Boot
  • Spring WebFlux
  • Micronaut
  • Hibernate
  • OpenAPI
  • JUnit
  • Testcontainers
  • Cucumber

Data & messaging

  • Kafka
  • Solace
  • RabbitMQ
  • PostgreSQL
  • Oracle
  • Redis
  • Liquibase
  • SQL / PL-SQL

Platform & cloud

  • Docker
  • Kubernetes
  • Helm
  • AWS
  • Linux
  • CI/CD
  • Gradle
  • Maven

Frontend & AI

  • Angular
  • React
  • TypeScript
  • LLM integration
  • AI tooling

@Contact

Let’s build something solid.

I’m open to freelance engagements — architecture, backend delivery, data platforms, AI integration or leading your team. Remote-first, based in Třinec, Czechia.

email josef@swsw.cz
phone +420 608 710 419
location Třinec, Czechia — remote friendly