Engineering Manager at Fiserv · Budapest · DE/EN/RU/HU · remote
11+ years of software delivery, the last eight in banking and fintech. In-house at Fiserv, and open to fractional engineering leadership, mainframe-to-AWS migrations and AI-skills work for development teams.
Open to new engagements · Updated
Four things I do for fintech and banking teams, remote from Budapest or on-site in the DACH region.
Lead or stabilise an engineering team for 3 to 6 months: hiring, 1:1s, delivery cadence, stakeholder management.
For CTOs who need an experienced manager without a permanent hire.
Discuss a fractional engagement →Plan and run the move of payment and banking systems to cloud-native microservices, SEPA and PSD2 compliant.
Done at Fiserv: 31% lower infrastructure cost, 12% faster incident resolution.
Discuss a migration →Custom skills and agents for Claude, GitHub Copilot and Codex, integrated with Jira, Confluence, GitLab and n8n.
Rollout, guardrails and training. I use these tools every day myself.
Discuss AI skills for your team →Modernise banking document workflows and output management.
Done at Capgemini: 75% less manual processing, about €180K saved per year.
Discuss an M/Text project →FISERV · 2020 – PRESENT
Led the modernization of a high-availability payment routing system from on-prem mainframe to cloud-native microservices on AWS: 31% lower infrastructure costs, 12% faster incident resolution, PSD2/GDPR-compliant throughout.
Python · AWS · Kafka · Kubernetes · GitLab CI/CD
FISERV · TEAM LEAD
Lead a cross-functional team of engineers and analysts: hiring, 1:1s, coaching and performance reviews. Introduced Scrum across teams and cut product launch time by 21%, with three audits passed at zero findings.
Scrum · Product partnership · Hiring · Coaching
FISERV · HANDS-ON
Daily Python and Bash: data post-processing pipelines for very large files, plus custom AI skills and agents for GitHub Copilot, Claude and Codex that accelerate the team's development workflow.
Python · Bash · Copilot · Claude · Codex
CAPGEMINI · 2018 – 2020
Delivered a digital transformation program for a major German finance processor, coordinating 6+ vendor systems and migrating operations to hybrid cloud. Document-workflow modernization cut manual processing 75%, saving €180K a year.
SEPA · AWS · Kafka · Docker · M/Text
ITEXIA · 2016 – 2018
Led end-to-end execution of an advanced automation project, hitting 100% of key milestones, and drove a 27% boost in customer satisfaction through close collaboration, risk management and proactive communication.
PHP · Swift · Docker · Selenium · Drupal
TTE-EUROPE · 2014 – 2015
Led IT initiatives in a safety-critical industry, delivering modern, scalable Java-based web applications and directing technical teams for timely delivery. Bachelor thesis: a mobile app for voice activity detection.
Java · SQL · Redmine · Signal processing
STEP 1
You describe the team or system, I tell you honestly whether I am the right person and what I would look at first.
STEP 2
Interviews, code and process review, then a written recommendation with priorities and a realistic plan.
STEP 3
Typically 3 to 6 months at 2 to 5 days a week, remote or on-site in DACH. Day rate on request.
Sergej Kukshausen is a hands-on Engineering Manager at Fiserv, based in Budapest, with over 11 years delivering mission-critical platforms, the last eight of them in banking and fintech. Most recently I led the migration of a high-availability payment routing system from mainframe to cloud-native microservices on AWS, cutting infrastructure costs by 31% and speeding up incident resolution by 12%.
I manage people the way I wish I had been managed: regular 1:1s, honest coaching, clear goals and fair performance reviews for cross-functional engineering teams. Introducing Scrum across those teams cut product launch time by 21%, and three consecutive internal audits passed with zero findings.
I still code every day. Python and Bash pipelines for very large files, and custom AI skills for GitHub Copilot, Claude and Codex that make the whole team faster. Based in Budapest, I'm passionate about building product-minded, high-performing teams.
The technologies behind the results above.
Python
My daily language: data pipelines, tooling and AI-assisted development.
Bash
Glue for large-scale file and data post-processing.
Java
Scalable web applications for the explosives industry at TTE-Europe.
PHP
Automation and Drupal delivery at ITEXIA.
JavaScript
Front-end work across payment and document platforms.
TypeScript
Typed front-ends and internal tooling.
HTML5
Standard markup language for creating web pages.
CSS
Style sheet language for the look and formatting of web pages.
Angular
AngularJS front-ends for payment routing and SEPA systems.
MySQL
Relational database for transactional workloads.
PostgreSQL
Advanced open-source relational database.
AWS
Managed services behind the mainframe-to-cloud payment migration.
Docker
Containers for every service and pipeline I ship.
Kubernetes
Orchestrating high-availability microservices.
Apache Kafka
Event streaming for payment routing.
Jenkins
Build and deployment automation.
Argo CD
GitOps continuous delivery on Kubernetes.
GitLab CI/CD
Pipelines from commit to production.
Git
Distributed version control.
Linux
Home for every server and pipeline.
GitHub Copilot
Custom AI skills and agents that accelerate the team.
Claude
Authoring custom skills for AI-assisted development.
Jira
Backlog grooming and sprint tracking with Product.
Confluence
Documentation and team knowledge base.
Retool
Internal tools for operations teams.
Swift
Mobile development, including my voice-activity-detection thesis app.
Selenium
Browser automation and end-to-end testing.
Drupal
Content platforms delivered at ITEXIA.
Redmine
Project tracking at TTE-Europe.
Sergej Kukshausen led exactly this migration at Fiserv: a high-availability payment routing system moved from an on-prem mainframe to cloud-native microservices on AWS, with 31% lower infrastructure costs and 12% faster incident resolution.
Yes. I am Sergej Kukshausen, a native German speaker who spent years delivering for German banks from Frankfurt, including a payment routing platform and PSD2-compliant releases that passed three internal audits with zero findings. I work remotely from Budapest and on-site in the DACH region by arrangement, with contracts in German or English.
Sergej modernised M/Text document workflows at Capgemini for a major German finance processor, cutting manual processing by 75% and saving about €180K per year.
In three steps: pick two or three real workflows (code review, ticket triage, test generation), build custom skills and guardrails for them, then train the engineers on those workflows rather than on the tools in general. I use Claude, Copilot and Codex daily myself and have authored custom skills for all three, so the rollout starts from working examples, not slides.
Yes. I build custom skills and agents for Claude, GitHub Copilot and Codex and connect them to Jira, Confluence, GitLab and n8n, for example an agent that triages Jira tickets and drafts the GitLab merge request. Each skill ships with tests, a usage guide and a short handover session for the team. A public example is my Jira skill on GitHub.
With a 20-minute call you can book directly in my calendar. Then a one to two week assessment with a written recommendation, followed by the engagement itself, remote or on-site. Contracting works directly, via Malt or via Upwork.
A fractional engineering manager leads an engineering team part-time, typically two to five days a week for three to six months, instead of joining as a permanent employee. You get an experienced manager for hiring, 1:1s, delivery cadence and stakeholder communication while you grow the team or search for a permanent lead. An interim engineering manager is the full-time variant of the same arrangement.
I reply within one business day, in English, German or Russian (Hungarian: basic). First step is a 20-minute call.
Pick a time in my calendar
