Mariusz Kotas
I build products
14 years of building large distributed systems for healthcare, e‑commerce and finance ‑ most recently Bitcoin and Lightning payments at Strike, now applied AI and algorithmic trading.
From hospital systems to Lightning payments.
I have 14 years of experience working on large, distributed, scalable systems ‑ across healthcare, e‑commerce and financial domains. I’ve helped scale software architectures to large teams and to a large number of customers.
Alongside that, I’ve shipped many products end‑to‑end ‑ some as freelancing engagements, many as open‑source. Most of them are tools I needed and use myself. The focus is on well‑crafted solutions: high quality, clean code, and good software practices.
I do my best work with real ownership: small senior teams, short feedback loops and a direct line from idea to production. My focus is Bitcoin, Lightning, crypto, algorithmic trading, machine/reinforcement learning and AI, and applying ML/AI inside real products.
What I’m working on.
One company, several open‑source things, and an applied‑AI direction I’m exploring.
Mitil
Applied AI for quantitative trading and market mechanics. We operate at low time frames ‑ combining raw data infrastructure, ML research, and a custom execution engine to extract alpha and deploy heavy quantitative strategies across crypto and prediction markets.
mitil.ai ↗Day‑to‑day focus areas
Things I’ve shipped.
A mix of open‑source primitives and end‑to‑end products. The open‑source side is where I keep the tools sharp.
nostr-client
Pure C# nostr client with built‑in reconnection, error handling and a clean reactive API. Build relays, bots and clients on top.
premium-tracker
Tracks premium on selling options on Interactive Brokers (IBKR). Built for the Wheel strategy ‑ covered calls and cash-secured puts.
strike-btcpayserver-plugin
BTCPay Server plugin that integrates Strike payments ‑ Lightning and on‑chain ‑ into self‑hosted merchant flows.
websocket-client
Pure websocket client with built‑in reconnection and error handling. Used in production by hundreds of .NET teams.
crypto-websocket-extensions
Higher-level extensions on top of the crypto exchange websocket clients ‑ aggregated order books, trades, and market data across Bitfinex, Bitmex, Binance and more.
Mitil
Applied machine learning on crypto markets. Quantitative trading and market mechanics at low time frames.
AirCase
Free casebook of US plane crash and accident investigations, with an AI search that shows the evidence instead of writing answers.
OpenGUI
GUI builder for any OpenAPI / Swagger spec. Generate a usable interface from a spec, in seconds.
Mañana Capital
Co‑founded a fully automated quantitative crypto trading desk. I built Nexus (back‑office) and TraXBot (HFT execution engine).
Where I’ve worked.
Healthcare, e‑commerce, finance, and Bitcoin ‑ large teams down to a desk of one.
Founder
Building applied‑AI trading systems end‑to‑end: market‑data infrastructure, ML research and a custom execution engine for crypto and prediction markets.
Senior Software Engineer
Bitcoin and Lightning Network payments infrastructure. Banking and finance services. Remote engineering on payments at scale.
Solutions Architect & Tech Lead
Greenfield enterprise distributed system, 150+ modules. Microservices on Kubernetes / Linkerd, .NET Core, GraphQL.
Co‑founder
Built and ran a fully automated quantitative crypto trading desk. Authored Nexus (back‑office) and TraXBot (HFT execution).
IT Contractor ‑ freelance
Long arc of freelance engagements: Flexiana, Adnext (crypto), Dastai, RABOT Energy, Zap Solutions / Strike, and others.
Senior Software Developer
Innovative R&D projects on .NET Core and Angular 2.
Software Developer
Hospital information system, chemical process simulator, and a framework for rapid development of large information systems.
Software Developer (C#)
Operating‑system shell designed for elderly users.
Say hello.
Best reached by email. I read every message myself.