Senior FullStack Engineer

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior FullStack Engineer based in Brazil. Join a remote-first engineering team building reliable, modern business systems and payment solutions for growing companies. As a Senior FullStack Engineer, you will develop and ship features for a prepaid card and payments platform, combining hands-on software engineering with AI-assisted development. You will use tools such as Claude Code to accelerate implementation while applying strong engineering judgment to review code, debug complex issues, and validate changes through rigorous testing. Working across backend services, frontend applications, databases, cloud infrastructure, and payment integrations, you will help ensure that financial transactions and sensitive customer data remain secure and reliable. The role emphasizes problem-solving, accountability, and delivering production-ready software rather than simply generating code. You will also benefit from dedicated learning time, paid certifications, and the flexibility of a distributed working environment. Accountabilities: As a Senior FullStack Engineer, you will take ownership of delivering reliable software changes across a complex payments ecosystem. You will combine AI-assisted implementation with careful code review, comprehensive testing, and a strong focus on financial accuracy, data security, and the end-user experience. - AI-Assisted Development: Use Claude Code as your primary development tool to plan changes, direct AI agents, review generated code, refine implementations, and deliver production-ready features. - Code Review and Quality Assurance: Identify incorrect, incomplete, or unsafe AI-generated code, independently assess its quality, and ensure that all changes meet engineering standards. - Testing and Validation: Write targeted tests that demonstrate the original issue and verify the fix, while ensuring existing user journeys continue to work correctly.

- Full-Stack Engineering: Build and maintain backend services using C# and . NET 8–10, Azure Functions, ASP. NET APIs, Entity Framework Core, and Dapper. - Frontend Development: Develop and maintain web and mobile applications using React, React Native, TypeScript, JavaScript, and Angular. - Database and Data Management: Work with MySQL, SQL Server, Cosmos DB, Azure Cache for Redis, queues, and related data systems to maintain reliable data processing and access. - API and Integration Development: Build, troubleshoot, and maintain APIs and integrations with card processors, payment and payout partners, identity verification providers, and messaging services. - Cloud Infrastructure and Delivery: Work with Azure Functions, Azure App Services, Key Vault, Application Insights, Terraform, Bitbucket Pipelines, and private NuGet packages hosted through Azure Artifacts. - Payment Reliability and Security: Investigate edge cases involving transaction timeouts, duplicate debits, refunds, inconsistent application and server behavior, and unauthorized access to customer or card data. - Cross-Layer Debugging: Trace issues across frontend applications, backend services, APIs, databases, and external integrations to identify root causes and implement dependable solutions. - Production Ownership: Deliver tested changes, communicate progress clearly, and take responsibility for the quality, reliability, and real-world impact of your work. Requirements: The ideal candidate is an experienced full-stack engineer who has already incorporated AI coding agents into real-world software delivery. You should be able to understand unfamiliar codebases, independently debug problems across the application stack, and recognize risks that automated tools may overlook. Strong attention to detail is essential, particularly when working with financial transactions and sensitive customer information.