About Me | Tanner Barcelos

Greetings! I’m Tanner Barcelos, a Senior Full Stack Engineer at Visa specializing in building internal platforms and developer tools that accelerate ML/AI engineering at scale. Over the past 3+ years, I’ve founded and architected platforms serving hundreds of engineers, transforming fragmented systems into unified developer experiences.

I thrive at the intersection of developer tools, AI workflows, and modern web technologies. My drive comes from building platforms that multiply engineering productivity—tools that feel more polished than consumer products and that engineers genuinely love using.

What I’ve Built

Fusion (Visa’s ML Platform) — I invented and built Fusion from zero to serving 200+ ML engineers and data scientists across four business units. Think Vertex AI, but built from scratch to unify five disparate ML systems into one cohesive platform. Within 18 months, Fusion became the standard for how ML work gets done at Visa, handling thousands of model deployments with 90% faster deployment times. What I’m most proud of: adoption was organic—engineers chose it because it genuinely made their work better.

AIOS Console (Hyperscale AI Operations) — I architected the operational control plane for Visa’s Hyperscale AI Platform, achieving 99.999% availability through dual-stack infrastructure design. Built real-time deployment UIs with WebSocket streaming, automated stack failovers that reduced switchover time from 10+ minutes to 5 seconds, and created server inventory tools that scan 500+ machines in 3 seconds (down from 2 hours).

80+ Production Interfaces — I delivered Visa’s first WCAG Level AA compliant AI platform applications, proving that accessibility and performance aren’t trade-offs. These interfaces feature GraphQL queries optimized to cut page loads from 8s to 1.2s, real-time streaming that lets users watch deployments happen live, and design-to-code workflows so tight that Figma mocks translate 1:1 to production. Engineers tell me these tools feel more polished than many consumer applications—that’s the bar I hold internal platforms to.

How I Work

High Agency & Rapid Iteration — I don’t wait for perfect specs. I ship prototypes, sit with users as they try them, and refine based on what I see. When researchers needed to query production data without learning SQL, I shipped an NL-to-SQL tool with LangChain in weeks. When infrastructure teams struggled with manual failovers, I built automated solutions that reduced intervention by 95%.

Product-Minded Engineering — I believe the best platforms emerge from deep user empathy. I partner directly with ML engineers, data scientists, and infrastructure teams to understand their workflows and pain points. Then I translate that understanding into technical solutions that feel obvious in hindsight but required real product thinking to discover.

Full-Stack Expertise — I architect GraphQL federation gateways that orchestrate microservices, build React 19 frontends with modern patterns (TanStack ecosystem, Vite), and engineer Go REST APIs that power Kubernetes/Nomad orchestration at scale. But the stack is just a means to an end—what matters is shipping tools that make engineers’ lives better.

Zero-to-One Builder — I’ve founded platforms from scratch and grown them to hundreds of users. I define API contracts, align technical direction across cross-functional teams, and drive execution from conception to delivery. I led the migration from legacy frameworks to modern React, improving build times by 60% and developer velocity by 40%.

Technical Depth

Frontend — React, TypeScript, GraphQL, TailwindCSS, TanStack Router/Query, Vite, Playwright, WebSockets. I build production-grade interfaces with strict accessibility compliance and obsessive attention to performance.

Backend — Go (Gin), Node.js, GraphQL Federation, REST APIs, Python, LangChain. I design resilient architectures that connect web applications with complex infrastructure while maintaining scalability.

Platform Engineering — Docker, Kubernetes, Helm, Terraform, GitHub Actions. I build and operate the infrastructure that supports mission-critical ML platforms across distributed environments.

AI/ML Integration — LangChain, prompt engineering, LLM integration. I leverage AI to create more intuitive developer experiences and build tools that make complex workflows accessible.

What Drives Me

I’m genuinely excited about building tools that shape how engineers work. There’s something deeply satisfying about watching someone go from frustrated by infrastructure to shipping features faster than they thought possible. That moment when adoption becomes organic because the platform just works—that’s what I chase.

I believe we’re at a civilization-defining moment where AI fundamentally reshapes human potential. The tools we build now will determine how billions of people collaborate with these systems. I want to be part of building those foundational platforms—tools that amplify what humans can achieve while keeping creativity and control firmly in their hands.

What’s Next

I’m drawn to opportunities where I can combine deep technical work with strategic impact—roles where I’m building platforms from scratch, defining technical direction, and shipping tools that hundreds or thousands of engineers depend on daily. I’m particularly excited about:

Developer platforms for AI systems where great UX multiplies entire team productivity
Research tools that accelerate frontier AI work through thoughtful abstractions
Zero-to-one opportunities where I can found platforms and grow them to scale
Mission-driven teams building technology that makes the world meaningfully better

Let’s Connect

Whether you’re exploring opportunities in developer platforms, AI tooling, or want to chat about GraphQL federation, React performance optimization, or building internal tools that engineers love—I’d be happy to connect.

Building platforms that multiply engineering productivity, one interface at a time.