# Sr. Frontend Engineer (ReactJS)

> Unpack Holdings Limited · Argentina (Remote) · Full-time · Posted 2026-06-16

**Workplace:** remote

## Description

### The Mission

We are looking for a Senior Frontend Engineer who doesn’t just build web pages, but masters the browser. This is not a role for a generalist who occasionally dips into React or relies heavily on pre-made component packages. We are looking for someone who has spent years deeply immersed in raw JavaScript and the modern React ecosystem—someone who intimately understands rendering lifecycles, state synchronization, browser performance, and pixel-perfect UX execution.

You will play a critical role in architecting our core platform. We build our UI from the ground up to ensure absolute performance and customizability, which means you will care deeply about writing clean, unbloated code, optimizing complex data layers, and bringing interfaces to life with fluid animations.

We value technical sovereignty, craftsmanship, and raw execution over corporate bureaucracy. If you want to own your architecture, solve genuinely difficult rendering challenges, and ship code at lightspeed, we want to talk to you.

### Key Responsibilities

-   **Core Frontend Architecture:** Architect, scale, and maintain our high-performance React and TypeScript applications from the ground up, avoiding unnecessary third-party package dependencies.
-   **Performance & Rendering Optimization:** Proactively identify and destroy rendering bottlenecks, memory leaks, and layout thrashing. Optimize for code-splitting, lazy loading, and sub-millisecond interaction states.
-   **Data Layer Management:** Build and optimize highly efficient frontend data flows and caching strategies utilizing React Query and GraphQL.
-   **Custom Component Engineering:** Design and maintain our proprietary, highly reusable component library from scratch. Fully document and stress-test components inside **Storybook**.
-   **High-Fidelity Interaction & Animation:** Work closely with product design to implement fluid micro-interactions and complex web animations that elevate the user experience.
-   **Technical Leadership & Code Quality:** Set the standard for frontend engineering excellence through rigorous code reviews, architectural documentation, and mentorship of junior/mid-level engineers.

## Requirements

-   **Deep React & JavaScript Expertise:** Years of production-level experience building complex, highly interactive web applications using React, TypeScript, and modern browser APIs.
-   **Advanced Data Fetching:** Deep, hands-on experience structuring scalable data caching, mutation, and synchronization strategies using **React Query** and **GraphQL**.
-   **Zero-Dependency Mindset:** A strong ability to build custom UI components, layouts, and logic _without_ leaning on bloated pre-built UI packages.
-   **Storybook Mastery:** Proven experience building, isolating, and documenting component systems inside Storybook.
-   **Rendering & Framework Internals:** A comprehensive understanding of how React (and ideally other frameworks like Vue.js) works under the hood (e.g., Virtual DOM reconciliation, fiber architecture, browser rendering pipelines).
-   **Communication & Timezone Alignment:** Strong professional English communication skills. Ability to work within a schedule that bridges **Eastern Europe and EST business hours**.

### Nice to Have

-   High proficiency with web animation libraries such as **Framer Motion, GSAP, Motion One**, or raw CSS/Canvas animations.
-   Experience with multi-framework architecture (e.g., transitioning or maintaining systems across **Vue.js** and React).
-   Familiarity with backend ecosystems like Elixir, or full-stack web performance considerations.
-   Experience working in high-velocity startup environments, gaming, fintech, or digital entertainment platforms.

## Benefits

### **Why Join Us?**

We offer more than just a standard software engineering seat; we offer the runway to drive the technical destiny of a global powerhouse.

-   **Extreme Architectural Sovereignty:** We value raw execution, system health, and clean code over bureaucratic red tape. If your design framework is robust and ready, you deploy it.
-   **A Culture of High-Talent Momentum:** Work alongside a highly competent, autonomous team that moves at lightspeed, actively supports your professional growth, and celebrates breakthroughs.
-   **High-Growth Upside:** We value "potential over pedigree." For a Senior Software Engineer who takes relentless ownership of end-to-end problems and systematically scales our platform's capacity, there is a clear, unrestricted runway into senior architecture and engineering leadership.

## Apply

[Apply at Unpack Holdings Limited](https://apply.workable.com/unpack-holdings-limited/j/181FC55F75/apply)

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