Senior Full Stack Engineer

Ciklum is looking for a Senior Full Stack Engineer to join our team in Brazil.

We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live.

About the role:

As a Senior Full Stack Engineer, you'll become a part of a cross-functional development team engineering experience of tomorrow. In this role, you will become part of a small, senior product engineering team for an established US mental health platform where clients book licensed psychologists and psychotherapists, complete with US insurance integrations and subscription billing. You will take full end-to-end ownership of product features—from frontend architecture to backend services and cloud deployment—leveraging a modern stack based on React, TypeScript, Python, PostgreSQL, and Google Cloud Platform (GCP).

Responsibilities:

End-to-End Feature Delivery: Design, implement, and deploy robust full-stack features from initial concept through production rollout

Frontend Architecture: Own and evolve the frontend architecture, including component libraries, design systems, state management, and clear module boundaries for the engineering team

Backend & API Development: Build and maintain scalable backend services and APIs (REST, GraphQL, or gRPC), covering authentication, RBAC, billing workflows, and audit logging

Code Quality & Testing: Write clean, secure, and maintainable code; establish and drive a risk-based testing strategy with strong end-to-end test coverage

Internal Tooling & AI Adoption: Develop internal productivity tooling (CLIs, agent-based workflows) and proactively utilize AI coding tools as force multipliers

Engineering Excellence & Mentorship: Conduct rigorous code reviews, champion engineering best practices, and mentor teammates in adopting modern standards

Cross-functional Collaboration: Partner closely with product management, UX/UI design, and executive leadership to shape the roadmap and guide core UX decisions

Requirements:

Experience: 6+ years of commercial software engineering experience, with a proven track record of building and scaling SaaS products as a Full Stack Engineer

Communication: Upper-Intermediate to Advanced (Fluent) English proficiency, both written and spoken

Software Design & Architecture: Demonstrated experience designing solutions for complex features and maintaining comprehensive technical documentation

Deep understanding of API architectural styles (monolith, microservices, serverless), design patterns, and engineering standards

Hands-on experience defining frontend architecture (design systems, shared component libraries) utilized by multiple developers

Proven ownership of critical product domains from discovery to launch (e.g., onboarding, billing, access control)

Software Development: Strong proficiency in TypeScript, modern JavaScript, HTML5, CSS3, and advanced React patterns

Solid background in Node.js or Python building high-performance backend services; willingness and ability to work primarily in a Python / FastAPI codebase

Strong relational database skills in PostgreSQL (data modeling, schema design, complex queries, and aggregations)

Practical commercial experience with distributed systems and event-driven patterns using message brokers (Kafka, RabbitMQ, SQS, etc.)

Quality Assurance: Hands-on experience with modern testing frameworks across the stack (e.g., Jest, Vitest, Playwright, Cypress, pytest)

Ability to define, track, and maintain code quality metrics; familiarity with observability, monitoring, and logging tools

DevOps & Cloud Deployment: Practical knowledge of containerization (Docker) and CI/CD pipelines (GitLab CI, GitHub Actions)

Experience deploying, configuring, and operating backend services on