Senior Full-Stack Software Engineer (Frontend-Focused)

About the RoleTassel is seeking a senior full-stack software engineer with a strong frontend focus to join us for greenfield development and legacy modernization projects. As a Senior Full-Stack Software Engineer, you will focus primarily on frontend development with React, Next.js, and TypeScript, while also contributing to backend services in .NET and SQL Server. You will help define technical direction, deliver high-quality solutions, and support the team through mentoring and collaboration.Key ResponsibilitiesContribute senior-level expertise to the frontend rewrite of a legacy application using React, Next.js, and TypeScriptDefine and implement best practices for frontend performance, accessibility, and maintainabilityBuild and maintain automated testing suites with Vitest and PlaywrightCollaborate with UI/UX designers and product managers to deliver intuitive, high-quality user experiencesContribute to backend services in C#/.NET and SQL Server as needed to support frontend functionalitySupport containerization and cloud deployment with Docker and Azure App Services (or Kubernetes)Mentor engineers and participate in code reviews and technical architecture discussionsEnable increased agentic development and debugging through iterative architectural, observability, and process improvementsRequired Skills & Experience7+ years of software engineering experience with strong expertise in React, Next.js, and TypeScriptStrong understanding of frontend architecture, performance, and accessibility best practicesExperience modernizing or rewriting legacy applicationsWorking knowledge of modern .NET applications (or equivalent) and SQL Server for backend integrationFamiliarity with CI/CD pipelines such as Azure DevOps or GitHub ActionsHands-on experience with containerization (Docker) and/or container deployment/orchestration (Azure App Service, Kubernetes, etc)Strong collaboration, communication, and mentoring skillsKnowledge of distributed systems and cloud architectureFamiliarity with agentic coding tooling such as Claude Code