ZENQMS2022 — PRESENT
Reliable platforms.
Less operational friction.
Senior DevOps Engineer. Cloud infrastructure, delivery workflows, automation and observability are the focus of my platform engineering practice.
A CONNECTED WAY OF THINKING
+PLATFORM ENGINEER · RESEARCHER · BUILDER
Engineering
systems.
Understanding
complexity.
I build reliable platforms and study how complex systems behave. My work connects infrastructure, software and the people who depend on them.
ONE SYSTEM. MANY CONNECTIONS.
01 /THE THROUGHLINE
Good engineering makes
complexity manageable.
From keeping large e-commerce environments running to designing cloud workflows, the question has stayed the same: how can this system become more reliable, repeatable and easier to operate?
Today, I work at the intersection of platform engineering and software. Research in complex systems adds another lens: understanding the connections, dynamics and trade-offs behind what we build.
02 /ENGINEERING IN PRACTICE
Built for the real world.
From operating systems at scale
to giving teams better ways to build.
Reliable platforms.
SANTANDER BRASIL2016 — 2018
10,000+
nodes in a heterogeneous environment
Consistency
at scale.
A highly available Chef ecosystem, cookbook CI and baseline configurations for a critical private-cloud environment. Training operations teams was part of the work.
WALMART ECOMMERCE2015 — 2016
2,000+
servers in the production environment
Reliability where
it matters.
Production operations, active-active data centers, performance tuning and provisioning automation. Built tooling to give development teams more autonomy.
Experience and scale from my professional history. These figures describe the environments I worked in.
03 /RESEARCH & SYSTEMS THINKING
UNIVERSIDADE DE SÃO PAULO · 2024
What happens
between
the nodes?
A master's in Complex Systems Modeling shaped the way I think about networks, emergence and dynamics. SPKMC brings that perspective into executable, open-source experiments.
SPKMCRESEARCH SOFTWARE / PYTHON
CONCEPTUAL NETWORK · NOT A SIMULATION RESULT
Epidemic dynamics,
explored through networks.
An implementation of the Shortest-Path Kinetic Monte Carlo approach for SIR epidemic modeling. Reproducible experiments, network models and interactive analysis.
Python + NumbaNetwork scienceStreamlit + Plotly
Software implementation by Marcus Castro. Based on the SP-KMC method by Tolić, Kleineberg & Antulov-Fantulin (2018).
Read the original method04 /BUILDING IN THE OPEN
Code, with a community.
Open-source AI.
Global impact.
I help maintain OpenClaw, an AI assistant that runs on your own devices and works through the messaging apps you already use. With over 390,000 GitHub stars, it ranks among the platform’s most-starred open-source projects, ahead of Linux, Kubernetes and TypeScript.
My work spans core reliability, WhatsApp integration, community code review and stable SDK contracts, helping a fast-moving ecosystem evolve without breaking what others build on it.
See my contributionsPUBLIC GITHUB ACTIVITYSnapshot · Oct 1, 2026
ORIGINAL PROJECT
spkmc
Research software for epidemic dynamics on networks.
Python ★ 5MAINTAINEROpenClaw
An open-source AI assistant with worldwide reach. I help maintain its core and plugin ecosystem.
TypeScript Upstream projectPUBLIC CODEThe rest of the work
Original projects, experiments and the repositories I contribute to.
Browse repositories on GitHub05 /THE PERSON BEHIND THE SYSTEMS
Marcus CastroSão Paulo, Brazil
Hands-on engineering.
A wider lens.
I've worked in IT since 2007, across infrastructure, operations, DevOps and platform engineering. I enjoy taking messy operational problems and turning them into something stable, repeatable and maintainable.
My academic path runs through networking, data science and complex systems. Alongside my day-to-day work, I explore AI agents, local inference and the ways software can help us understand and operate complex systems.
QUESTIONS I'M EXPLORING
My full professional history on LinkedInHow can agents support engineering teams? Where should a system's boundaries sit? How do local interactions create global behavior?
A PATH THROUGH SYSTEMS2007 — 2026
ZenQMS
Senior DevOps Engineer
Epos Now
Platform Engineer
Velocity Technology Solutions
DevOps Engineer
Santander Brasil
Site Reliability Engineer
Walmart eCommerce
Systems Administrator · Sr. Systems Engineer
The foundations
IT support, networks and Linux systems
ACADEMIC FOUNDATION
Universidade de São Paulo
MSc, Complex Systems Modeling · defended 2024
Universidade Presbiteriana Mackenzie
Graduate diploma, Data Science · 2018–2020
FIAP
Network Infrastructure · 2013–2015
06 /KEEP THE CONVERSATION GOING
Interesting systems.
Good conversations.
Platform engineering, open source, complex systems or a technical question worth exploring.
contato@mcaxtr.me