Senior Front-End Engineer (React.js)

Darwoft

Location: Buenos Aires, Argentina
Job Type: full-time
Salary: Unknown
Posted: August 20, 2025

Job Description

Get to Know Us

At Darwoft, we create software that drives real change. But were more than just tech were people first. We believe in building human-centered digital experiences and having fun while we do it. Our team is curious, passionate, and always growing. Based in Latin America, weve been partnering with companies worldwide to develop innovative solutions with heart and purpose.

We work remotely, collaboratively, and with a strong sense of community always embracing a culture of continuous learning, good vibes, and real impact.

About the Role

Were seeking a Senior Front-End Engineer to join a high-impact project in the life sciences industry. Youll be responsible for designing and implementing sophisticated, intuitive interfaces that bring AI-powered applications to life solutions that support medical professionals in making critical decisions and improving patient care.

This is a senior-level role with significant ownership: youll influence the technical direction, contribute to architectural decisions, mentor team members, and transform complex workflows into seamless user experiences.

What Youll Be Doing

Architect, build, and maintain advanced front-end applications with React.js as the primary framework (Vue.js experience is a plus)
Design innovative human-AI collaborative interfaces that accelerate professional workflows
Create intuitive, performant user interfaces that make complex AI capabilities accessible to life sciences professionals
Own critical user-facing features end-to-end, from concept to production
Collaborate closely with product managers, designers, and engineers to deliver customer-focused solutions
Optimize applications for high-performance data visualizations and AI-powered interactions
Define and promote front-end best practices, coding standards, and reusable patterns
Mentor junior engineers and foster a culture of technical excellence
Troubleshoot complex issues across the stack and support production systems
Continuously improve the user experience through data-driven decisions

What You Bring

5+ years of experience building complex web applications with React.js (Vue.js a strong plus)
Strong expertise in HTML, CSS, JavaScript (ES6+), TypeScript, and Node.js
Proven experience with front-end architecture and scalable design patterns
A passion for crafting exceptional user experiences with a solid understanding of UX/UI principles
Strong communication skills, comfortable engaging with both technical and non-technical stakeholders
Ability to thrive in a collaborative environment while working independently when needed
A mindset of curiosity, adaptability, and continuous learning

Nice to Have

Experience migrating Vue.js applications to React.js
Knowledge of Web Components and Design System development
Familiarity with GCP technologies (Cloud Run, API Gateway, BigQuery, etc.) in production environments
Hands-on experience with async operations, modular development, dependency injection
Startup environment experience and proactive ownership of solutions

What Darwoft Offers (Contractor)

Contractor agreement with payment in USD
100% remote work
Argentinas public holidays
English classes
Referral program
Access to learning platforms

🎯 Who is this job for?

This role is ideal for a Senior Front-End Engineer with 5+ years of experience in React.js, TypeScript, ES6+, and scalable front-end architecture, plus strong UI/UX sensibilities. The position focuses on building AI-powered, user-centric applications in the life sciences sector, owning critical features end-to-end, and mentoring junior developers. It suits someone from LATAM who thrives in remote, collaborative environments, has experience with complex data visualizations, and enjoys shaping best practices for high-impact, user-facing solutions.

💬 Potential Interview Questions

How would you architect a large React app for AI-assisted workflows?
Use a feature-modular structure (domain folders), server state via React Query, colocated hooks, and a design system; isolate heavy AI/UI logic behind service hooks and Context to keep components pure and testable.
What patterns do you use to manage async AI interactions (streaming, long-running jobs)?
Leverage SSE/WebSockets for streaming tokens, React Query for polling and cache invalidation, idempotent mutation keys, and optimistic/rollback updates with abortable requests.
How do you make human-AI collaboration UIs trustworthy for clinicians?
Expose model confidence and provenance, provide clear affordances for overrides/edits, log decisions, and design for error prevention and explainability (inline rationales, “why” links).
How do you optimize performance for large, interactive data visualizations?
Window/virtualize lists and charts, memoize selectors and props, offload heavy work to Web Workers, prefer Canvas/WebGL for dense plots, and batch state updates to minimize re-renders.
What TypeScript techniques improve safety in complex UI states?
Enable strict mode, model UI state with discriminated unions and exhaustive switch checks, use generics for reusable hooks, and define branded types for domain identifiers.
How would you design and consume APIs on GCP (Cloud Run + API Gateway) from the front end?
Use API Gateway for auth/rate limits, call Cloud Run services with OAuth/OIDC ID tokens, centralize fetch logic with interceptors/retries, and cache/read-through via React Query.
How do you ensure accessibility in a healthtech app handling critical decisions?
Follow WCAG 2.1 AA, use semantic HTML and ARIA only when needed, guarantee keyboard and screen-reader flows, manage focus on async updates, and validate contrast and error messaging.
How would you migrate a Vue.js module to React without halting delivery?
Adopt a strangler pattern: wrap legacy routes, build new React screens behind feature flags, map Vuex to React Query/Zustand, and share tokens/components via a design system or Web Components.
What front-end security practices are essential for PHI/PII?
Use HTTPS and secure cookies (HttpOnly/SameSite), never store secrets in the client, redact logs/analytics, enforce CSP, and gate sensitive actions with scoped tokens and audit trails.
How do you test AI-powered UIs end-to-end?
Unit test pure logic and hooks, contract test API clients with mocked providers, and run Playwright/Cypress E2E against stubbed AI endpoints plus visual regression for critical workflows.

📋 Job Summary

Darwoft is hiring a Senior Front-End Engineer (React.js) based in LATAM to build AI-powered healthcare applications for a high-impact Life Sciences project. This remote contractor role involves architecting advanced interfaces, leading UI development in React (Vue.js a plus), mentoring engineers, and optimizing data-rich, AI-driven workflows. Ideal candidates have 5+ years’ experience with modern JS/TS, Node.js, and a passion for UX. Darwoft offers USD compensation, remote flexibility, English classes, and a learning-focused culture—perfect for engineers seeking purpose-driven work with global impact.