Senior Frontend / Product Engineer building fast, accessible product experiences and applied-AI systems.

Open to remote full-time roles, long-term contracts, and selected freelance engagements. I design and ship interfaces that scale — accessible, fast, type-safe — and own the full stack behind them, including AI products: hybrid retrieval, BYOK chat, and LLM integrations with Claude, DeepSeek & OpenAI.

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~/portfolio/me.json

{
  "name": "Josué Cortés",
  "role": "Senior Frontend / Product Engineer · Fullstack & Applied AI",
  "location": "El Salvador",
  "status": "Open to full-time, contract, and selected freelance work",
  "stack": [
    "React 19",
    "Next.js 16",
    "TypeScript",
    "Tailwind v4"
  ],
  "backend": [
    "NestJS",
    "Postgres + pgvector",
    "Drizzle",
    "Inngest"
  ],
  "ai_tooling": [
    "OpenAI API | Claude API | DeepSeek API",
    "LLM Integration",
    "RAG pipelines"
  ],
  "now_building": "DocAI — hybrid retrieval + bounded agent loop (M6 live)"
}▋

What I do

Focus Areas

Performance

Building interfaces that load fast and stay fast — optimizing bundles, images, and rendering paths to meet real user expectations.

Accessibility

Writing semantic HTML, maintaining keyboard navigation, and testing with screen readers so products work for everyone.

Real-time UX

Designing optimistic updates, live sync, and responsive interactions that make collaborative tools feel instant.

AI Integration

Connecting LLMs to product workflows — streaming responses, RAG pipelines, and patterns that keep users in control of the model.

Where I've worked

Industry Expertise

Real Estate

Designing and developing scalable Microfrontend, enterprise-level platforms for managing real estate agent ecosystems, following strict Agile practices (Kanban/SCRUM).

Pharmacy Benefit Management (PBM) and Reimbursement Systems

Designing and developing scalable platforms for PBM and reimbursement systems. Managing complex healthcare ecosystems using Agile/SCRUM methodologies.

Financial Services

Designing, developing, and deploying Digital Banking platforms for a new financial institution. Integration of diverse government and private payment gateways across multiple channels, defining technical architecture scope, and championing Agile/SCRUM methodologies for project implementation.

Insurance Technology

Managed the implementation of core banking and insurance platforms, focusing on achieving regulatory compliance (Compliance) and robust transactional security protocols. Expertise in end-to-end claims and claims lifecycle management.

Featured work

Projects

Live

Mini Linear

Realtime Kanban with optimistic UI and full keyboard control.

Next.jsConvexdnd-kit

Verified evidence

Realtime

Optimistic + rollback

Access

5 auth paths

A11y

Keyboard-first

Architecture decision

Convex backend for realtime state instead of hand-rolled WebSocket infra — honest trade-off: ships faster, less control over the sync layer.

Repo Live demo

Live

DocAI

Document Q&A with hybrid retrieval, RRF, evals, guardrails, and a bounded agent loop returning cited answers.

Next.jsPostgres + pgvectorClaude + DeepSeek API

Verified evidence

Retrieval

Hybrid + RRF

Evaluation

Hit@5 0.90

Agent

Bounded + cited

Architecture decision

Hybrid retrieval — Postgres full-text + pgvector combined with Reciprocal Rank Fusion — instead of vector-only search, to catch exact-term matches vector search misses.

Repo Live demo

Live

Aurora Product Page

Premium product page focused on UI craft and performance.

ReactViteTypeScriptTailwind

Verified evidence

A11y

Lighthouse 100

Quality

axe-clean

Motion

Reduced-motion safe

Architecture decision

Hand-tuned animations gated behind prefers-reduced-motion instead of a general-purpose motion library, to keep the bundle light and respect user settings.

Repo Live demo

Live