Thien Dao

I’m a Senior Front-end Engineer with 4+ years building React, Next.js, and TypeScript applications across startup and outsourcing environments. I approach features from the user’s side, consistently proposing improvements—not just executing tasks. Recently, I drove the frontend of a multi-tenant SaaS eLearning MVP, owning security and performance decisions while partnering closely with backend and product to ship what genuinely works for users. I migrated permissions to a role-and-permission RBAC system with 9 custom roles, re-architected auth from localStorage tokens to httpOnly cookies enforced in Next.js middleware, and eliminated both flash-then-redirect and an XSS token-theft vector. I also split rendering by route (server-rendered auth-gated and SEO pages, client-rendered interactive learning pages), then used TanStack Query to cache and dedupe requests with per-data-type invalidation. On top of that, I built a FE-first workflow on a small team (API contract first with mocked data), standardized an AI-assisted coding plan → review → implement process, and delivered a strong technical SEO foundation with 92+ Ahrefs Site Health and a 92 Lighthouse score.