(HN/ HCM) Senior Fullstack Engineer (AI)

DescriptionCrossian is a high-growth technology-driven e-commerce business. As a start-up formed in 2020, we have created a fast-paced and dynamic environment, enabling our people to reach a cumulative average growth rate of over 1000% in the last 5 years.We're forming an elite Fullstack squad that operates differently, working with AI-driven products. No "that's not my ticket" culture. Each engineer owns a feature end-to-end - from data model to UI pixel - and thinks like a Product Owner when scoping, like a Solutions Architect when designing, and like a craftsman when coding.If you want to work with people like that and become like them, this is the next step.What you'll doFeature ownershipTake a feature from kick-off to production: data model, API design, service layer, UI.Own reliability, performance, and observability of what you ship - not just the happy path.Turn product goals into concrete technical specs.System design & architectureDesign full-stack architectures: databases, APIs, queues, caches, frontend rendering strategies.Apply patterns (Clean Architecture, Event - Driven, etc) where they fit the problem.Write design docs and lead technical discussions.BackendBuild well-tested APIs and microservices in Node.js, Go, or Python - whichever fits.Design and optimize relational and non-relational databases.Work with event streaming.FrontendBuild fast, accessible, SEO-friendly storefronts with React / Next.js (SSR/CSR as appropriate).Optimize Core Web Vitals, bundle size, lazy loading, and CDN strategy (Cloudflare, AWS S3).Write maintainable state management (Redux, Zustand, Recoil).Code quality & collaborationWrite clean, tested, well-structured code; review teammates' code.Treat unit/integration/e2e testing and CI/CD as standard practice.Work with Product and Design to shape requirements, not just receive them.Support junior engineersRequirementsEducation & ExperienceEducation: Strong academic background in Computer Science, Engineering,...5+ years of professional engineering with real fullstack work. We value T-shaped engineers who have a clear spike (deep expertise) in either Frontend or Backend, but possess the full-stack capability to own and ship a feature end-to-end when needed2+ years building products at a product company, fast-growing tech startup, or environments demanding strong product-led delivery.Built or joined at least one system from scratch: schema, API, service, and UI.Technical Depth & Domain KnowledgeWe don't gate-keep on language, but you should understand the why behind your choices.Must have at least one stack in depth:TypeScript / JavaScript: Node.js, React, Next.js (SSR, API routes, state management),Node / Go / Java: backend services, goroutines, clean service architecturePython: API backends, scripting, data-adjacent servicesLLM / AI integration in production featuresDatabases (required):Relational design: normalization, indexing, query optimization, transactions (PostgreSQL preferred)At least one NoSQL store in production (Redis, MongoDB, Elasticsearch)Able to diagnose and fix a slow querySystem-level:Async systems: queues, events, background workersJudgment on when caching helps vs. when it creates problemsMonolith and Microservice trade offsNice to have:eCommerce: checkout flows, inventory, pricing engines, ad integrationsDocker, Kubernetes basics, CI/CD pipeline ownershipBenefitsOwnership: Direct ownership of real work streams from day 1 with a clear trajectory toward product leadership roles.AI Implementation: Hands-on experience deploying cutting-edge AI solutions to solve high-scale business problems.High-performance Team: Work with a data-driven team that values autonomy, speed, and outcomes.Compensation: Competitive total compensation package (13 months guarantee + attractive bonus).Health & Leave: 15 paid leave days + global health insurance.Learning Budget: Dedicated L&D budget to support your professional development.