Senior Full Stack Engineer

We are looking for a highly experienced, strictly hands-on Senior Full Stack Engineer (Python) to join a senior engineering team. You will drive the delivery and modernization of a complex B2B SaaS platform used by global enterprise clients. In this role, you will build new product modules end-to-end, from technical specification through to production deployment, while modernizing a mature codebase. Responsibilities: Build new platform modules end-to-end: translate business requirements into technical specs (use cases, data models, API designs) through to production deploymentExecute modernization of the Python/Flask codebase - clean layered architecture, reduced technical debt, improved testabilityAct as quality gate for all AI-generated code - catching logic errors, security issues, and architectural violationsPartner with the Intelligence Systems Engineer on features touching the AI/agent layerCollaborate with the Angular Architect on API contracts and frontend integrationWrite operational documentation: changelogs for QA, operations guides for DevOps, architecture docs for developersProactively identify and address security concerns during developmentMin requirements: Proven commercial experience as a Senior Backend or Full Stack Engineer, actively engaged in hands-on coding (no pure advisory roles). Strong proficiency in modern Python, with a focus on writing clean, type-safe, and well-documented code. Solid experience with Python web frameworks (e.g., Flask, FastAPI, Django) and a good understanding of web application architecture. Expertise in relational databases (preferably PostgreSQL), SQL, and schema design. Strong security mindset with a proven ability to identify, understand, and mitigate real-world web vulnerabilities. Hands-on experience using AI coding tools (Copilot, Cursor, Claude) as part of your daily workflow, paired with a critical eye for reviewing AI-generated code. Experience working with containerization (Docker, Kubernetes) and background processing systems (e.g., Redis, Celery). Excellent independent problem-solving skills and the ability to navigate complex codebases. Would be a plus: Proven experience decomposing monolithic/legacy codebases into a clean, layered architecture. Hands-on modernization experience within mature, production-grade SaaS products. Familiarity with Python ORMs (e.g., SQLObject, SQLAlchemy). We offer: Opportunity to work on bleeding-edge projectsWork with a highly motivated and dedicated teamCompetitive salaryFlexible scheduleBenefits package - medical insurance, sportsCorporate social eventsProfessional development opportunitiesWell-equipped officeAbout us: Grid Dynamics (NASDAQ: GDYN) is a leading provider of technology consulting, platform and product engineering, AI, and advanced analytics services. Fusing technical vision with business acumen, we solve the most pressing technical challenges and enable positive business outcomes for enterprise companies undergoing business transformation. A key differentiator for Grid Dynamics is our 8 years of experience and leadership in enterprise AI, supported by profound expertise and ongoing investment in data, analytics, cloud & DevOps, application modernization and customer experience. Founded in 2006, Grid Dynamics is headquartered in Silicon Valley with offices across the Americas, Europe, and India.