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

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

Remote · Full-time

About Ubiminds

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.

Challenge

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.

What You'll Do

• 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.

Required Skills & Qualifications

• 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).

Soft Skills (Critical)

• 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.

Nice to Have

• 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.

Team & Environment

• 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.

Why Join

• Work on core platform systems with real business impact.
• Be part of a team evolving toward modern architectures and AI-driven development.
• Collaborate in a highly dynamic and learning-oriented environment.
• Full support from Ubiminds with HR, career guidance, and administrative services.
• Remote-first culture with international exposure.

About Ubiminds

Our Culture

• People First. We are all about people!
• Challenge yourself. There's always room for improvement and continuous improvement is in our essence.
• Make it happen. Be ready to take challenges as they come. It's all about attitude and commitment.
• We're in this together. We work as a team, thrive as a team, and evolve as a team.
• Averaging on awesome. We work hard to deliver high-quality services and look forward to exceeding expectations.
• Keep it real. We promise you honesty, transparency, and openness, regardless of the situation.

Perks and Benefits

• You are placed in a product-based company, with the same treatment as their full-time employees.
• Have our full back-office support, from career guidance to HR and concierge services.
• Enjoy our remote-first policy – we are a distributed team, after all.
• Get your own MacBook (none of that "bring your own device" stuff here).
• Have access to growth opportunities with other amazing technology professionals, through tech talks, chapter meetings, and even remote happy hours for tons of fun!
• Improve your English through free lessons with a native English speaker - get to the next level on your communication skills!
• Candidate Referral bonus (promote Ubi to your tech friends, and get paid for it!)
• Miss working in the office? Our cool Florianópolis headquarters is available, whenever you want, with weekly quick massages & tasty snacks, soft drinks, and games