Krzysztof.
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Full-Stack Developer & Infrastructure Engineer

I build software that ships and the servers it runs on.

I'm Krzysztof (Chris) Sliwinski. I write the code, design the interface, deploy it to a Linux box I administer myself, and keep it online. Web platforms, mobile apps, game servers, and the infrastructure underneath them.

See my work Download resume
45K+
Lines of Java shipped
3
Production servers run
5
Languages in production
Full-Stack Web Mobile Apps Linux Infrastructure Game Server Dev
How I work End to end, no hand-offs Real users, not toy projects I own the deploy and the uptime Self-taught, then proven in production
Selected work

Projects I've built and run

Each of these is live, used by real people, and maintained by me. No tutorials, no clones.

Feudline

A competitive Minecraft factions server, and the 45,000-line plugin that powers it.

Feudline is a Paper 1.16.5 server I designed, coded, and operate on my own. Rather than bolting together existing plugins, I wrote the entire gameplay layer from scratch as a single Java plugin: 201 classes spanning factions and territory claiming, a power and raiding system, a player-driven economy with an auction house, KOTH and envoy events, crates, bounties, custom enchants, a skill tree, private vaults, perks, ranks, and a full inventory-GUI framework behind all of it.

It runs on a dedicated Ubuntu VPS I administer under systemd, with YAML and JSON persistence, LuckPerms and Vault integration, and live config reloads so I can ship balance changes without dropping players.

201Java classes
~45KLines of code
20+Gameplay systems
1Developer

Java · Paper / Bukkit API · LuckPerms · Vault · systemd · Ubuntu

Systems written from scratch

  • Factions
  • Territory & power
  • Economy
  • Auction house
  • KOTH
  • Envoy
  • Crates
  • Bounties
  • Custom enchants
  • Skill tree
  • Private vaults
  • Perks
  • Ranks
  • Kits
  • Warps & homes
  • Shop
  • Chat channels
  • Nametags
  • Cosmetics
  • Moderation suite
  • Vein miner
  • GUI framework

Software & platforms

Oddology Dashboard

Co-founder · Full-stack developer

A multi-tenant SaaS platform in Node.js and React that runs a real agency: clients, projects, contracts, billing, and a client-facing portal. I built role-based access control with near real-time session enforcement, a consent-aware analytics engine with PDF and XLSX export, and backend services for site integrity monitoring, automated backups, and domain provisioning.

Node.js · Express · React · SQLite · Stripe

LifeLogr

Solo mobile developer

A health and lifestyle tracking app built in Flutter and Dart, currently in closed testing on Google Play. It handles calorie and macro tracking, barcode scanning, AI-powered nutrition label parsing from photos, workout logging, journaling, and sleep and weight tracking, driven by a notification engine that adapts to each user's logged activity and intake patterns.

Flutter · Dart · Firebase · AI/OCR · Google Play

High-Availability Hosting Stack

Infrastructure engineer

Three Linux VPS servers I provision and administer, hosting every site and app I run. A primary web host is shadowed by a hot standby that receives continuous file, certificate, and vhost syncs, while a third box runs a 10-second health monitor that calls the provider's API to move a failover IP and rebind it over SSH if the primary goes down.

Ubuntu · Apache · PM2 · Let's Encrypt · rsync · Bash

OddoBot

Developer & operator

A Discord bot running in production alongside a separate dev instance, backed by a Lavalink audio node and a Stripe-connected API for paid features. Deployed under PM2 with its own marketing and dashboard sites, and versioned so I can test breaking changes against the dev bot before they touch users.

Node.js · Discord.js · Lavalink · Stripe · PM2

Client work — live in production

FieldLedger

Lead developer · app.tscpm.com

A custom business management app built to retire a client's 50-tab Excel workflow across three companies. One login covers all of them: job logging from the field, PDF invoice generation, invoice delivery by email and SMS, payment tracking, payroll with running per-employee totals, and a revenue and expense dashboard. It handles real payroll and invoicing data, so it's typed end to end, validated at every boundary, session-hardened, and audit-safe by design, with soft deletes so financial history can never be destroyed. Built mobile-first, because the owner logs jobs from his truck.

React · TypeScript · Vite · Tailwind · Express · Drizzle · SQLite · Twilio · PDFKit

Snake River Retail

Developer · snakeriverretail.com

A retail business site I rebuilt from scratch after migrating it off Wix, then extended well past a brochure site. Behind the static front end runs an Express backend powering a customer voting and giveaway system with bcrypt-hashed admin auth, cookie sessions, transactional email, and an admin panel the owner uses himself. Proxied through Apache, managed under PM2, and live on the infrastructure I run.

Node.js · Express · bcrypt · Nodemailer · Apache · PM2

TSC PM Co.

Designer & developer · tscpm.com

The web presence for a property management company: a custom-coded marketing site, plus a separate rental listing page for one of its properties. Designed and built from scratch with SEO and schema markup, launched with SSL, and kept online under an ongoing maintenance retainer. I also run the Google and Facebook ad campaigns that feed it.

HTML/CSS/JS · UI design · SEO & schema · Apache · Ads

Interface & brand design

Designer

I design the products I build. Layout, type, color systems, motion, and the small interaction details that make an interface feel finished, including this site and the design system behind it. Dark mode, scroll-driven reveals, and reduced-motion support are baseline for me, not extras.

UI/UX · Design systems · Motion · Accessibility

Toolkit

What I work with

The stack I actually ship in, grouped by where it lives.

Languages

What I write day to day.

  • Java
  • JavaScript / Node
  • Dart
  • Python
  • C++ / C#
  • SQL & Bash

Front-end & design

Interfaces people actually enjoy using.

  • React
  • Modern HTML & CSS
  • Flutter
  • Design systems
  • Motion & interaction
  • Responsive & a11y

Back-end & data

The layer everything depends on.

  • Express & REST APIs
  • SQLite & PostgreSQL
  • Auth & RBAC
  • Stripe integration
  • Firebase
  • AI / LLM integration

Infrastructure & IT

Where the code goes to live.

  • Linux VPS administration
  • Apache, SSL, DNS
  • PM2, systemd, cron
  • Failover & backups
  • Active Directory, Okta, M365
  • Git & security fundamentals
Experience

Where I've done the work

Client engineering, my own products, and enterprise IT.

Co-Founder & Full-Stack Developer

2023 – Present

Oddology LLC · Remote

  • Built and operate a production SaaS dashboard used by real paying clients for projects, analytics, and billing.
  • Implemented multi-tenant role-based access control with near real-time session enforcement.
  • Wrote backend services for site integrity monitoring, automated backups and restores, and domain provisioning.
  • Deploy and administer the Linux VPS fleet the whole company runs on, including failover and monitoring.
  • Design, build, and maintain live client sites end to end, then run the SEO and ad campaigns that feed them.

FieldLedger — Lead Developer

Launched Apr 2026

Custom business management app · app.tscpm.com

  • Lead developer on a greenfield app replacing a client's 50-tab Excel workflow across three companies, behind a single login.
  • Built field job logging, PDF invoice generation, invoice delivery by email and SMS, payment tracking, payroll with running per-employee totals, and a revenue and expense dashboard.
  • Handles real payroll and invoicing data, so it's typed end to end, validated at every boundary, session-hardened, and soft-deleted only, keeping the financial audit trail intact.
  • Built mobile-first down to a 375px viewport, because the owner logs jobs from his truck.
  • Delivered and still maintained, hosted on the VPS fleet I administer.

React · TypeScript · Vite · Tailwind · Express · Drizzle · SQLite · Lucia · Twilio · PDFKit

TSC PM Co. — Designer & Developer

Launched Jan 2026

Property management company · tscpm.com

  • Designed and built the company's website from scratch, no template and no page builder, and launched it with SSL on infrastructure I administer.
  • Implemented SEO and schema markup, and run the Google and Facebook ad campaigns that feed the site.
  • Added a separate rental listing page for a managed property, live since May 2026.
  • Maintain the site under an ongoing hosting and maintenance retainer.

HTML/CSS/JS · UI design · SEO & schema · Apache

Snake River Retail — Developer

Launched Dec 2025

Retail business · snakeriverretail.com

  • Rebuilt the site from scratch after migrating it off Wix, giving the owner code he actually owns.
  • Extended it well past a brochure site with an Express backend powering a customer voting and giveaway system.
  • Built bcrypt-hashed admin authentication, cookie sessions, transactional email, and an admin panel the owner runs himself.
  • Proxied through Apache and managed under PM2 on the VPS fleet I administer.

Node.js · Express · bcrypt · Nodemailer · Apache · PM2

Solo Developer — Feudline & LifeLogr

2024 – Present

Independent projects

  • Sole developer of a 45,000-line Java plugin suite powering a live Minecraft factions server.
  • Built LifeLogr, a Flutter health tracking app now in closed testing on Google Play.
  • Ship AI-assisted features, including nutrition label parsing from photos.

Windows Upgrade Technician

Sep – Oct 2025

Power Construction LLC · Contract via Aline Consulting · Chicago, IL

  • Upgraded 120+ employees from Windows 10 to Windows 11 within a single-month engagement.
  • Handled imaging, device setup, troubleshooting, and asset preparation.

IT Technician I

Oct 2024 – Feb 2025

AIT Worldwide Logistics · Contract via LaSalle Network · Palatine, IL

  • Drove a post-acquisition ServiceNow queue from the low four figures down to under 100 open items, closing 400 to 500 tasks a month.
  • Provisioned and decommissioned users across Active Directory, Okta, and Microsoft 365 with clean audit trails.
  • Imaged and deployed laptops across U.S. locations through a major acquisition transition.
  • Supported the Windows 10 to 11 migration and device remediation via Kaseya.

Computer Science

2023 – 2025

McHenry County College · previously Southern Illinois University

  • Studied computer science while working and shipping.
  • Continuing education in penetration testing fundamentals (TryHackMe) and Cisco networking, working toward the CCNA.
About me

I like owning the whole thing

Most of what I know, I learned by needing it to work.

I started building because I wanted things that didn't exist yet, and the fastest way to get them was to write them. That turned into a company, a SaaS platform, a mobile app in testing, a game server with its own engine of custom systems, and a small fleet of Linux servers I keep online.

The part I care about most is the whole loop: understanding the problem, designing the interface, writing the backend, deploying it, and being the person who gets paged when it breaks. I've done enterprise IT work too, and it made me better at the boring, important things like access control, clean audit trails, and not breaking production.

Get in touch
Code on screen
Crystal Lake, IL
Open to remote & Chicago area
Contact

Let's build something

Hiring, freelance, or just want to talk shop? My inbox is open.

Get in touch

I read everything that comes in and reply within a day.

Emailchris.sliwinski@gmail.com Phone+1 (630) 524-3868
LocationCrystal Lake, IL · Remote friendly