Description
**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 contract 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 / accessibility testing.
* GitGuardian, Veracode, or Sonatype.
* AI\-powered testing or development agents.
**Perks and benefits**
* **Growth without limits:** build your skills through mentorship, internal TechTalks, challenging projects, and a dedicated annual learning budget
* **Competitive compensation:** get recognition that reflects your skills and impact, with regular performance and compensation reviews
* **Flexibility:** work 100% remotely with flexible hours that support focus, autonomy, and a healthy work rhythm
* **Meaningful, modern projects:** build impactful products using modern technologies alongside global teams and leading brands
* **Collaborative culture:** join a supportive environment with zero micromanagement where ideas are welcomed and contributions are recognized
* **Well\-being \& support:** access local well\-being programs and people\-focused support tailored to your location
Job Types: Full\-time, Contract
Contract length: 4 months
Work Location: Remote