Field notes / 01  ·  Juan Castro

Builder. Engineer. Creator.

I make useful software and the systems behind it—from product experiences and developer tools to infrastructure. I want to understand how the pieces work, where they meet people, and what makes them dependable.

My path runs through military service, data operations, Linux and cloud systems, SaaS engineering, and product software. That range keeps me interested in both the human task and the technical edges around it.

Employed · Full-Time

Human study / three working lenses

Portrait of Juan Castro
Three connected ways of working: turn ideas into tools, understand the system, and stay open to what can be made next.

02 / How I work

Curiosity gives the work direction.

  1. 01

    Builder

    Make an idea tangible: a useful tool, a clearer workflow, or a product someone can use.

  2. 02

    Engineer

    Understand the boundaries and operating conditions around the code, not only the happy path.

  3. 03

    Creator

    Stay curious, move between disciplines, and keep learning by making things.

03 / Selected chapters

A career shaped by systems and software.

Different environments, one recurring question: how can the work become clearer and more useful?

Product and data engineering

—

Software Developer III

RSR GROUP

As a Software Developer III, I spearheaded a data service migration to a new platform and created new business reports using Django/Python. Additionally, I optimized internal processes by developing enhanced functionality with JavaScript/React.

Streamlined development processes by developing and presenting a Git workflow productivity strategy to leadership, resulting in a 30% reduction in development time.

Earlier systems and operations work

  • Mailgun

    Senior Infrastructure Engineer

    SaaS · Reliability · Infrastructure

  • Rackspace

    Systems Architect

    Linux · Cloud · Databases

  • Travelocity

    Backend Developer / Data Operations

    SQL · Analysis · Operations

  • US Army

    Military Service

    Operations · Discipline · Systems Thinking

04 / Working range

A broad toolkit, applied to the question at hand.

Languages
TypeScript · Python · Go · SQL
Backend
Node.js · Fastify · Next.js · Prisma
Databases
Postgres · MySQL · SQLite · ClickHouse
Infrastructure
Linux · Docker · NATS · AWS
Developer Tooling
GitHub Actions · CI/CD · Observability · Automation

Independent projects presented here refer to my own implementations and repositories. Project names may overlap with unrelated products, services, or organizations.