Senior Full Stack Engineer

Senior Full Stack Engineer Position Type: Full-Time, Remote Working Hours: U.S. Business Hours About the Role We are looking for an experienced Senior Full Stack Engineer to lead the development of a modern, AI-assisted tax filing platform. This is a highly technical, hands-on engineering role where you'll design system architecture, build scalable backend services, develop intuitive frontend experiences, and ensure every part of the application is accurate, secure, and production-ready. You'll own features from concept to deployment, working across both frontend and backend while using AI development tools like Cursor and Claude Code to accelerate delivery and improve code quality. The ideal candidate enjoys solving complex engineering problems, takes ownership of technical decisions, and thrives in environments where data accuracy and reliability are critical. Responsibilities Full Stack Development Design, build, and maintain scalable full-stack applications. Develop secure backend services and REST APIs using Python and FastAPI . Build responsive, user-friendly frontend interfaces for complex workflows and data entry. Integrate frontend applications seamlessly with backend services. System Architecture & Engineering Design application architecture, data models, APIs, and service structures that support long-term scalability. Make technical decisions around performance, maintainability, and reliability. Refactor and improve existing systems as the platform evolves. AI-Assisted Development Use Cursor and Claude Code as part of your daily development workflow. Leverage AI tools to improve productivity, code quality, debugging, and implementation speed. Continuously evaluate opportunities to automate development tasks. Data Validation & Reliability Implement robust validation logic, business rules, and error handling. Ensure data accuracy across complex workflows and user submissions. Build systems that are secure, reliable, and audit-ready. Testing & Quality Write comprehensive unit, integration, and end-to-end tests. Identify and resolve bugs before deployment. Maintain high code quality through testing, documentation, and code reviews. Collaboration & Ownership Own features from planning through deployment. Document technical decisions and communicate progress proactively. Work closely with product stakeholders to clarify requirements and deliver scalable solutions. What Makes You a Strong Fit You enjoy solving complex technical problems from end to end. You take ownership of systems rather than simply completing assigned tasks. You build clean, maintainable, and well-tested code. You communicate proactively and work effectively in a remote environment. You embrace AI-assisted development as part of your engineering workflow. You pay close attention to accuracy, especially when working with business-critical data. Required Experience & Skills Must-Have 5+ years of professional Full Stack Software Engineering experience. Strong expertise in Python and FastAPI . Experience designing and building production-grade REST APIs. Strong frontend development experience with modern JavaScript frameworks. Experience designing scalable application architecture and data models. Hands-on experience using Cursor and Claude Code in daily development. Experience building workflow-driven or form-heavy applications. Strong understanding of API integration, validation, authentication, and secure data handling. Experience writing unit, integration, and end-to-end tests. Excellent written English communication skills. Nice-to-Have Experience building tax, fintech, accounting, compliance, or other highly regulated applications. Experience with cloud platforms and modern deployment pipelines. Experience with relational databases and ORM frameworks. Familiarity with CI/CD pipelines and automated testing. Experience working in fully remote engineering teams. What Does a Typical Day Look Like? Your day begins by reviewing updates from teammates and planning development priorities. You'll spend most of your time building new features, designing APIs, implementing frontend functionality, and solving complex workflow challenges. Throughout the day you'll use Cursor and Claude Code to accelerate development, write tests, troubleshoot issues, and improve implementation quality. You'll collaborate with product stakeholders to clarify requirements, document technical decisions, and ensure every feature is accurate, scalable, and ready for production. Key Performance Indicators (KPIs) Quality and reliability of delivered features API performance and system scalability Code quality and test coverage Accuracy of business logic and validation Timely delivery of development milestones System stability and production reliability Documentation quality Collaboration and ownership Interview Process Initial Recruiter Screening Technical Assessment / AI Evaluation Client Technical Interview Offer Stage What Happens After You Apply Right after you apply, you'll receive an email invitation from Spark Hire to record your Intro Video. It's a short, self-recorded introduction completed on your own time and serves as the final step in completing your application. This allows hiring managers to evaluate your communication skills before moving forward with interviews, making the hiring process faster and more efficient. Please keep an eye on both your inbox and spam folder for your Spark Hire invitation. #LI-AG1