Senior Full-Stack Software Engineer (.NET, React, AI)

About the role

3Pillar is looking for a high-velocity, adaptable Full Stack Software Engineer to join a fast-paced product team building a brand-new MVP from the ground up. The team works alongside an established engineering squad using modern AI-assisted software development, delivering code at exceptional speed with a daily delivery flow rather than multi-week sprints.

Key responsibilities

• Use AI coding tools (Claude Code, GitHub Copilot, Cursor, OpenAI) to run end-to-end user stories, refactor legacy logic and prototype features at a rapid daily cadence.
• Design and maintain scalable, cloud-native microservices with C# / .NET Core, Web APIs, Entity Framework Core and event-driven architectures.
• Build responsive user interfaces with React (TypeScript, functional components, hooks, Context API, Zustand/Redux).
• Work with AWS services (Lambda, SQS/SNS, Cognito, ECS, Docker) and integrate them into automated review pipelines and CI/CD workflows.
• Implement document lifecycle features, template creation, dynamic field population and e-signature integrations.
• Oversee automated code review guardrails, static analysis and unit testing (xUnit, NUnit, Jest, RTL) to validate AI-generated code.

Required profile

• 5+ years of hands-on engineering experience building and scaling production applications with C# / .NET Core and React (TypeScript).
• Daily hands-on use of AI coding assistants (Cursor, GitHub Copilot, Claude Code) with strong prompt and context engineering.
• Located in Latin America (Mexico or Brazil strongly preferred) for real-time collaboration with a US team; business-fluent English.
• Nice to have: e-signature integration experience, AWS certifications, MongoDB experience, and comfort in short, daily story cycles.

Required skills

• C# / .NET Core, Web APIs, Entity Framework Core
• React (TypeScript)
• AWS Lambda, ECS, SQS/SNS, Docker
• PostgreSQL or MS SQL Server, SQL optimization, RESTful microservices
• xUnit, NUnit, Jest, RTL

What we offer

• Medical insurance and life insurance as per company policy
• 12 days of paid vacation, sick leave and paid holidays as per local law
• Paternity and maternity leave, marriage, bereavement and graduation leaves
• Christmas bonus as per local law
• Saving fund, beach house managed by the Asociacion Solidarista, direct deposit of payroll and Udemy e-learning
• Remote-first work environment and a global team