Senior Full Stack Software Engineer – .NET (C#) / React - (516)

Remote · Full-time

Ubiminds is a GPTW-certified, people-first company that partners with American software product companies to scale their development teams. We connect Brazil’s top 5% talent with innovative U.S. companies through a unique combination of staff augmentation and employer-of-record services.

We are supporting a U.S.-based company looking for a Senior Full Stack Software Engineer to join a Platform product team (Lyons team), working on core systems and evolving platform capabilities.

We’re looking for a Senior Full Stack Engineer who thrives in highly dynamic environments, where priorities evolve and ambiguity is part of the day-to-day.

This role is ideal for someone who is technically strong but also highly adaptable, proactive, and ownership-driven — someone who can move across different domains, quickly understand complex systems, and contribute wherever needed.

You will work on critical platform areas such as messaging, scheduling, and automation, while helping drive the transition toward modern architectures and AI-enhanced development practices.

• →Develop and maintain features across front-end (React) and back-end (.NET / C#) systems.
• →Work on systems involving messaging (SMS, WhatsApp, email via providers like Twilio).
• →Build and evolve solutions for scheduling, calendar integrations, and event-driven workflows.
• →Contribute to a multi-repository environment with technologies such as C#, Python, and React.
• →Support the evolution toward microservices architecture, Kubernetes, and continuous deployment pipelines.
• →Collaborate in architectural and cross-team technical discussions.
• →Experiment with and adopt AI-driven development approaches across the SDLC.
• →Write clean, maintainable, and testable code.
• →Actively share knowledge and collaborate across teams.

• Strong experience with .NET (C#) in production environments.
• Solid experience building modern front-end applications with React.
• Experience with relational databases such as MS SQL.
• Experience working in complex, existing systems (not only greenfield).
• Familiarity with:
  • Microservices architecture
  • CI/CD pipelines
  • Containerized environments (e.g., Kubernetes)
• Ability to work across multiple technologies and codebases.
• Experience working in distributed teams.
• Strong communication skills in English (C1 level – written and verbal).

• Strong ownership mindset.
• Proactive, self-driven attitude (“figure it out” mindset).
• Ability to ask the right questions and clarify requirements.
• Comfortable dealing with ambiguity and changing priorities.
• Collaborative mindset, sharing knowledge and learnings.
• Ability to ramp up quickly in new domains and technologies.

• Experience with Python backend services.
• Experience with AI-assisted development workflows.
• Exposure to AWS environments.
• Experience with messaging platforms such as Twilio.
• Experience with event-driven systems or scheduling platforms.

• Platform product team (Lyons), working across multiple domains.
• Tech stack includes C#, React, Python, and distributed systems.
• Ongoing evolution toward microservices and modern infrastructure.
• Strong culture of collaboration, experimentation (including AI usage), and continuous improvement.