Senior Full Stack Engineer (CX Platform) (Buenos Aires)

Felix Technologies

3d•Remote

About The Position

Félix is building an AI-powered financial companion for Latinos in the United States, beginning with cross-border remittances and expanding into credit, savings, and wallet services. The company is transitioning its core operational capabilities from third-party low-code solutions to a scalable, in-house ecosystem. As part of the CX Platform team, the Senior Full Stack Engineer will own operational modules used daily by the CX team, building and shipping features end-to-end from React interfaces through Node.js services and data models. The role focuses on high-density data views, complex operational workflows, and internal tools that reduce cognitive load and handling times. It also involves building secure backend-for-frontend and aggregation layers that connect internal microservices and external providers while enforcing authorization. The engineer will work closely with business stakeholders to understand operational workflows, deliver practical solutions, maintain a high engineering quality bar, and mentor peers. The day-to-day technology stack includes React, TypeScript, modular CSS, Node.js, REST APIs, BFF patterns, relational databases such as PostgreSQL, RBAC, modern build tools, Git, and CI/CD. Félix emphasizes strong engineering fundamentals over prior experience with any particular tool.

Requirements

At least 5 years of experience as a Software Engineer in a fast-paced, dynamic environment.
Fluent or advanced English.
Advanced React and UI engineering skills, with a deep understanding of React and solid foundations in HTML/DOM, CSS, and HTTP.
Proficiency in TypeScript.
Ability to design and build well-structured REST APIs in Node.js.
Strong understanding of API design, service boundaries, error handling, and clean backend patterns.
Ability to design relational schemas, write performant queries, and reason about transactional integrity.
Hands-on experience implementing authentication and authorization flows, especially RBAC for sensitive data.
Ability to design BFF or aggregation layers that consume multiple microservices and expose a clean, secure interface to the client.
Excellent problem-solving skills, combining creative UI implementation with engineering rigor on the backend.

Nice To Haves

Experience mentoring engineers, raising the bar in code reviews, and influencing architectural decisions beyond immediate scope.
Experience building internal tools, CRM systems, or high-density data applications focused on operational efficiency and scale.
Experience in highly regulated sectors such as fintech or healthcare, including strict RBAC and data isolation.

Responsibilities

Build complete operational modules, from React user interfaces through Node.js services and data models.
Design and ship CX platform modules, including high-density data views, complex operational workflows, and internal tools.
Implement secure intermediary layers, including BFFs and aggregators, that consume internal microservices and external providers, standardize payloads, and enforce authorization.
Work closely with business stakeholders to understand daily workflows and translate them into technical solutions that reduce handling times.
Champion clean patterns, pragmatic design, and high-quality engineering across shipped modules.
Mentor peers and contribute to raising the broader engineering culture.