About the Role
We are looking for a Senior Full Stack Engineer to build and maintain features across React microfrontends, TypeScript serverless Lambda functions, and Fastify services for a corporate tax provision platform. You will develop AWS infrastructure with Terraform, maintain GitLab CI/CD pipelines, write tests using Jest and Playwright, and leverage AI coding tools as a core part of daily development within a large multi-repo codebase. The role spans modern TypeScript and a legacy ASP.NET codebase and runs as a project engagement through end of 2026.
What you will do
Build and maintain features across React microfrontends, TypeScript/Node.js serverless applications, and Fastify services.
Contribute to shared business logic across frontend and backend applications.
Develop and maintain unit, integration, and E2E tests.
Develop and deploy AWS infrastructure using Terraform.
Participate in GitLab CI/CD pipeline development and maintenance.
Collaborate with architects and product teams on APIs, async job patterns, and data layer abstractions.
Leverage AI coding assistants effectively within a large, multi-repo codebase.
Maintain the legacy ASP.NET Framework 4.7.2 application as needed during migration
Must haves
3+ years of strong TypeScript/JavaScript with Node 18+.
Proficiency with React 18 and modern React patterns.
Experience with React microfrontend architecture.
Experience with backend APIs and serverless applications using Fastify, NestJS, AWS Lambda, and API Gateway.
Experience with PostgreSQL.
Experience with AWS and Terraform.
Experience with Docker and GitLab CI/CD.
Experience with Jest, Playwright, and/or K6.
Hands-on experience with AI coding tools such as Cursor, GitHub Copilot, Claude Code, or equivalent.
Upper-Intermediate English level.
Nice to haves
Working knowledge of C# / .NET.
AG Grid and/or SpreadJS.
Stryker mutation testing.
OpenTelemetry / Grafana Faro.
Amplitude.
ASC 740 tax provision concepts or corporate tax software.
pa11y / acce