Senior full stack engineer with 10+ years on the web. Five years on client product teams at Gorilla Logic: payments and auth, production releases, geospatial tooling, e-commerce and real-time feeds. Before that, six years of creative engineering for American Express, Delta, Dunkin' and PlayStation. I build software with AI agents and still know exactly what got built: a written brief before any code, agents in parallel, and "done" is three commands, not an opinion. On client work, AI drafts and investigates; I validate every finding against the code and handle everything client-facing myself.
Selected work
Made 3D Secure mandatory for Japan. Owned the Stripe auth and payment flows on a US and Japan consumer platform, led the 3DS rollout, and ran production releases for the web apps from scope to post-release verification.
Explained a cross-application auth change. Mapped redirects, callbacks, gateway and identity provider, then gave the team an AI-generated interactive explainer, sequence diagrams and a flow spec, each step verified against the code.
Benchmarked models before using one. jev-bench scores TypeSafe's Jev against Claude Haiku 4.5 and Opus 5 on 72 labeled decisions with the same scoring code: Jev 94.4% at about 185 ms and $0.02 per 1k decisions, Opus 98.6% at 2.6 s and $6.40.
Kept PII out of LLM calls. pii-gate masks personal data in prompts as typed placeholders and restores it in the reply, with a per-category mask/block/allow policy and an audit log that never stores values.
Experience
Senior Full Stack Engineer · Gorilla Logic
to present
AI tooling for client and internal teams 2026
Built Claude Code skills for sprint refinement that read Jira tickets, map changes across two repositories, flag MuleSoft, Salesforce and carrier dependencies, and propose Fibonacci estimates with reasoning, split suggestions and refinement questions. Reviewed against the code and project context before anything reaches the team.
Used agents to trace a client bug across the front end, back end and production database; the trace surfaced a missing upstream integration record. Built diagramming skills to explain auth redirect flows to the team.
Built Gorilla Code, an interactive Claude Code training environment with tool hooks, activity logging, guardrails and a live dashboard, with MCP and multi-agent exercises.
Panasonic Well / Yohana · Senior Full Stack Engineerlate 2023 to early 2026
TypeScript, React, Next.js, Node, Express · Kotlin/Micronaut over gRPC, CockroachDB · Flutter · Stripe with 3DS, Auth0, Salesforce, Ably · EN-US and JA-JP i18n · Terraform, Docker, GitHub Actions
Built customer task creation and editing, including complex branching forms wired to backend services, and fixed navigation and state bugs that could hide questions or block a task flow.
Owned the auth and payment flows on Stripe and led the implementation that made 3D Secure mandatory for Japan users.
Owned production releases for the web apps: scope and timing with QA, product and the client, then build, deploy and post-release verification.
Managed Stripe coupon codes, CI/CD pipelines and telemetry as Terraform code, so promotions and pipeline changes went through review.
Cyngn · Senior Full Stack EngineerJan to Oct 2023
TypeScript, React · Python API · Mapbox, deck.gl, nebula.gl, GeoJSON
On the mapping editor for autonomous industrial robots, built the elevation-layer decomposition by geographic coordinates, which made terrain data readable and workable for the operators configuring routes.
The Pro's Closet · Full Stack EngineerMar 2022 to Jan 2023
Helped build the e-commerce storefront from scratch on Next.js Incremental Static Regeneration with the tech leads and UX team, and designed the app-wide React Context state management.
Led the Veriff identity-verification proof of concept, including the webhook handling design.
Implemented the activity feeds and real-time chat for a healthcare-professional networking platform, built Express endpoints and SQL migrations, and integrated Elasticsearch for content discovery.
Created reusable components in the shared Storybook library, aligned to the UX design system.
As Senior Creative Engineer, led six developers, handled direct client communication and mentored juniors. Drove the migration of legacy site functionality to React functional components and hooks, with REST API integrations for American Express, Delta, Dunkin' and Hertz.
Automated image optimization and JS/CSS minification with Grunt across client builds, cutting page-load times by up to 30%. Adopted by the whole team.
Built an accessible HTML email template system with cross-client compatibility on Salesforce Marketing Cloud; about 6% click-through improvement.
Built the PlayStation Thanksgiving 2019 interactive email: a CSS-only quiz with an interactive version and a static fallback, US and Canada variants in AMPscript, passed through a three-gate review.
Media Operations Technology Analyst · Bosz Digital / Prodigious
Claude Code skills and hooks, MCP, multi-agent orchestration, verification with compiler, lint and tests, prompt guardrails, rate limiting and cost control for LLM endpoints, model benchmarking (accuracy, latency, calibration, cost), PII masking
tennis-reservation (TypeScript). Books courts at midnight with parallel requests to the club's API in about 500 ms, 12x faster than the browser-automation version it replaced. github.com/stern9/tennis-reservation
Education
B.S. Computer Science, ULACIT
B.S. Business Management, Universidad Interamericana