Who's this

About

The human behind the terminal.

CLASS
Principal Engineer
LEVEL
ALIGN
Chaotic Good
XP
+17 years

Hi, I'm Sergio Marcial — Principal software engineer. Work in complex systems long enough and you become the person who draws the map, not because you planned to, but because you kept asking what was underneath. Good software is craft, not assembly line. Judgment over procedure. The parts nobody documented are usually the ones that matter, and hard problems teach you more than easy ones. I build things that ship: TypeScript frontends, Go backends, Kotlin services, and the occasional piece of glue code nobody wants to claim.

CURRENT QUEST

Building GenAI, distributed data systems at global scale as the day job. Side quest: open-source libraries and writing up what I learn along the way. Always rolling for initiative. Open to new adventures — drop a line if you want to party up.

WORKING DISCIPLINE

I don't think my side projects are interesting because of what framework they're written in. They're interesting to me because I build them under the same rigor I'd bring to anything, for an audience of exactly one person whose trust I genuinely could not afford to lose — because that person is me, in the middle of trying to change something real about how I live. I still write the decision down before I write the code, not because a design doc is impressive, but because it's the only way I've found to catch myself lying to myself about why I'm building something a certain way. I still do only the engineering the goal actually calls for, and skip the rest, because effort spent on a problem that doesn't exist is effort I don't have left for the problem that does. That discipline isn't something I put on for a code review. It's the same discipline that gets every one of these tools built, and so far, kept every promise.

Equipped

Loadout

Backend
  • Kotlin
  • Java
  • Go
  • Node.js
  • Python
  • Docker
  • Redis
  • MongoDB
  • PostgreSQL
Frontend
  • TypeScript
  • Svelte / SvelteKit
  • React
  • Node.js
Data Science
  • Python
  • SQL
  • Pandas
  • NumPy
  • Jupyter
AI
  • Python
  • LLMs
  • Vector DBs
  • RAG
  • Prompt Engineering
Familiar Proficient Expert Currently active
Reach me

Make contact

Open to new quests — senior & principal roles in backend, distributed systems, and AI systems or infrastructure