Senior Full Stack Engineer

Senior Full Stack Engineer (Python, FastAPI & AI-Assisted Development) – Remote

Position Type: Full-Time, Remote

Working Hours: U.S. Client Business Hours (with flexibility for sprint reviews, deployments, and production support)

About the Role

At the company, one of our clients is hiring a Senior Full Stack Engineer to architect and build a modern tax filing platform from the ground up.

This isn’t just another software engineering role.

You’ll own the architecture, backend services, frontend experience, and key technical decisions behind a mission-critical platform where security, scalability, accuracy, and reliability are essential.

You’ll work extensively with AI-assisted development tools such as Cursor and Claude Code to accelerate development while maintaining exceptional code quality and engineering standards.

If you enjoy solving complex technical problems, building scalable software, and taking ownership from architecture through deployment, this role is a strong fit.

What You’ll Own

Full-Stack Application Development

• Design, build, and maintain production-grade web applications.

• Develop secure backend services using Python and FastAPI.

• Build intuitive, responsive frontend interfaces for complex workflows.

• Design scalable REST APIs and service architectures.

• Integrate frontend and backend systems seamlessly.

• Deliver maintainable, high-quality software across the full application stack.

System Architecture & Technical Design

• Own end-to-end application architecture.

• Design scalable data models and service boundaries.

• Build systems designed for long-term maintainability and growth.

• Drive technical decisions that improve scalability, reliability, and performance.

• Identify technical risks early and recommend practical solutions.

Backend Development

• Develop secure REST APIs using FastAPI.

• Build business logic for workflow-driven applications.

• Integrate third-party APIs and external services.

• Optimize application performance and API responsiveness.

• Build reliable background jobs and asynchronous processing workflows.

Frontend Development

• Build responsive, user-friendly interfaces for dashboards, forms, and workflow management.

• Develop reusable UI components using modern JavaScript frameworks.

• Integrate frontend applications with backend APIs.

• Improve usability while maintaining accessibility and performance.

AI-Assisted Software Development

• Leverage Cursor and Claude Code throughout the software development lifecycle.

• Build AI-assisted engineering workflows that improve developer productivity.

• Use AI tools to accelerate implementation, debugging, testing, refactoring, and documentation.

• Continuously improve engineering workflows using emerging AI technologies.

Testing, Quality & Reliability

• Write and maintain:

• Unit tests

• Integration tests

• End-to-end tests

• Maintain high code quality standards.

• Improve platform reliability and application stability.

• Refactor code to reduce technical debt and improve maintainability.

Security & Data Integrity

• Implement robust validation, authentication, and authorization.

• Ensure secure handling of sensitive financial and user data.

• Follow security best practices throughout the application lifecycle.

• Build systems where data integrity and accuracy are critical.

Documentation & Collaboration

• Document architecture decisions, APIs, and technical implementations.

• Collaborate with product managers, engineers, and stakeholders across time zones.

• Participate in sprint planning, architecture discussions, and code reviews.

• Communicate blockers, risks, and technical recommendations proactively.

What Success Looks Like

• High-quality features delivered on schedule.

• Secure, reliable, and scalable application architecture.

• Strong automated test coverage and low production error rates.

• Maintainable, well-documented code.

• Effective collaboration across engineering and product teams.

• Continuous improvements to development workflows through AI-assisted tooling.

What Makes You a Strong Fit

• Think like an owner, not just a contributor.

• Proactively solve complex technical problems.

• Comfortable making architectural decisions.

• Strong attention to detail and software quality.

• Excellent communicator who collaborates effectively across teams.

• Passionate about scalable software, clean architecture, and continuous improvement.

• Excited to leverage AI tools to improve engineering productivity.

Required Experience & Skills

Experience

• 5+ years of professional Full Stack Software Engineering experience.

• Strong expertise with:

• Python

• FastAPI

• REST API development

• Experience designing and shipping production-grade applications.

• Strong frontend development experience using modern JavaScript frameworks.

• Experience building workflow-driven or form-heavy applications.

• Hands-on experience using:

• Cursor

• Claude Code

• AI-assisted development tools

• Experience with:

• PostgreSQL or similar relational databases

• Git

• API integrations

• Excellent written and verbal English communication skills.

Nice to Have

• Experience building:

• FinTech platforms

• Tax software

• Compliance platforms

• Financial systems

• Experience developing highly secure applications.

• Familiarity with distributed engineering teams and asynchronous collaboration.

• Experience designing scalable system architectures.

What a Typical Day Looks Like

• Review sprint priorities and engineering updates.

• Design and develop backend APIs with FastAPI.

• Build frontend features and workflow interfaces.

• Improve system architecture and technical design.

• Implement complex business logic and integrations.

• Use Cursor and Claude Code to accelerate development.

• Write automated tests and review pull requests.

• Document architecture decisions and collaborate with engineering teams.

In short: You’ll architect, build, and continuously improve a mission-critical software platform while owning technical execution from design through production.

Key Metrics for Success (KPIs)

• High-quality features delivered on time.

• Secure, scalable, and reliable application performance.

• Low production defect rates.

• Strong automated test coverage.

• Well-documented, maintainable code.

• Positive collaboration across engineering and product teams.

• Reduced technical debt and improved development efficiency.

Why This Role Stands Out

• Architect and build a mission-critical platform from the ground up.

• High ownership with direct technical impact.

• Work with modern AI-assisted engineering workflows.

• Solve complex engineering challenges in a collaborative environment.

• Fully remote role with flexible collaboration.

• Career growth opportunities into:

• Staff Engineer

• Technical Lead

• Engineering Manager

• Software Architect

Interview Process

• Application Review

• Spark Hire Intro Video (3–5 minutes)

• Technical Assessment

• Client Interview

• Offer & Onboarding

What Happens After You Apply

After submitting your application, you’ll receive an email invitation from Spark Hire to record a short 3–5 minute Intro Video . This is the first step in our hiring process and can be completed whenever it’s convenient for you.

Instead of multiple initial screening calls, you’ll have one opportunity to introduce yourself, discuss your full stack engineering experience, walk through projects you’ve built, explain your experience with Python, FastAPI, modern frontend frameworks, and share how you’ve used AI-assisted development tools such as Cursor or Claude Code to improve software development. Your video will be reviewed by the hiring team before moving to the technical assessment.

You can record your video as many times as you’d like before submitting it—only your final version will be reviewed.

Please keep an eye on both your inbox and spam folder for your Spark Hire invitation after applying.

Apply Now

If you’re passionate about building scalable software, leveraging AI to accelerate engineering, and taking ownership of complex technical challenges from architecture through deployment, we’d love to hear from you. Apply today and help build a secure, modern platform that delivers meaningful impact.