Full-stack developer · available for select work

Full-stack engineering for
mission-critical products.

I'm Sebastjan. I design and engineer secure, high-performance systems — from government messaging and enterprise identity platforms to EV networks and AI automation. Software engineering teams trust in production.

Sebastjan Lajković

Environments I've built for

  • Public sector
  • Norwegian enterprise
  • EV operators
  • Own products

Selected work

Delivered, measured, running.

A cross-section of what I've shipped — from public-sector infrastructure through to the products I'm building now.

01Live

SMS-Proxy

Government messaging gateway

A resilient government messaging gateway routing secure citizen notifications at scale — engineered for strict auditability, hardened security and zero-downtime reliability. Running in production for 6 years with minimal maintenance.

Node.jsDocker
02Live

IAM Platform

Identity & access, Norwegian market

Identity lifecycle and single sign-on for Norwegian customers — building Novell IDM drivers, user provisioning and access policies with Access Manager.

Novell IDMAccess ManagerSSO
03Live

EV Charging Platform

Fleet & driver management

An enterprise management app for EV charging fleets, driver sessions and automated billing — delivered full-stack with robust Keycloak identity infrastructure.

ReactNext.js.NETKeycloak
04In progress

Charge Sim

Charging simulation engine

A simulation engine for EV charging networks, built ground-up to model stations, load and protocols.

RustVueDockerSwarm
05In progress

Hive

AI automation for companies

A platform that helps companies design and run AI-driven workflows. My current product focus.

AstroVueRustAI
hive.seba4.org ↗
06Live

Fastbreak

End-to-end launch — web, hosting, email, domain

Took a startup's board game from idea to online in one engagement: brand-forward marketing site, domain and DNS, managed hosting, and professional email — fully set up and running. A fast, mobile-first, SEO-ready Astro build.

AstroWeb designHostingEmailSEO
fastbreakgame.com ↗
07Live

Creative Ad Builder

Drag-and-drop ad production at scale

A visual, drag-and-drop builder for producing interactive digital ad creatives — design once, then generate and adapt thousands of on-brand variations across formats and channels. Built for a leading ad-tech platform used by global brands.

VuePHPAd tech

“We came to Sebastjan with a name and not much else. He sorted out the whole thing — site, domain, hosting, email — and had us online without any fuss. It's quick, it works properly on a phone, and honestly I haven't had to think about it since.”

Miha KumarFounder · Fastbreak

“Six years on, the gateway he built is still pushing out citizen notifications every day without a hiccup. It just runs. Sebastjan was on our team back then, and even after he went out on his own we kept his number. When something actually matters, he's who we call.”

Engineering LeadGenlan d.o.o.

How I help

Scoped, priced and delivered up front.

01

Greenfield product builds

End-to-end web application engineering, from an empty repository to a scaled production environment. I take full ownership of architecture, delivery and system quality.

02

Secure & compliant systems

Identity, access and messaging infrastructure where zero-downtime reliability and absolute auditability are non-negotiable.

03

System rescue & scaling

Inherited a fragile, slow or tangled codebase? I audit, stabilize, optimize and refactor it into a maintainable asset.

About

A developer who reduces your risk.

I've spent my career on systems where getting it wrong is expensive — government messaging, identity and access, EV infrastructure. I bring that same discipline to every build, in Vue, Angular, React, .NET and Rust.

s4Labs is where I work in the open: shipping products like Hive, helping launch Fastbreak, and partnering with a small number of teams each year.

Let's talk about your project.

Tell me what you're building. I reply to every serious enquiry within a day — and if I'm not the right fit, I'll tell you honestly.

Open for new projects · Remote-first · CET timezone