Sr Engineer, Software - Full Stack [T500-27159]

Senior Engineer – Software Full Stack (API Gateway & AI Infrastructure)

About T-Mobile: T-Mobile US, Inc. (NASDAQ: TMUS), headquartered in Bellevue, Washington, is America's supercharged Un-carrier, connecting millions through its strong nationwide network and flagship brands, T-Mobile and Metro by T-Mobile. Customers benefit from an unmatched combination of value, quality, and exceptional service experience. TMUS India Private Limited, operating as TMUS Global Solutions, has engaged ANSR, Inc. ("ANSR") as its exclusive recruiting partner. That means that any communications regarding TMUS Global Solutions opportunities or employment offers will be issued only through ANSR and the 1Recruit platform. If you receive a communication or offer from another individual or entity, please notify TMUS Global Solutions immediately.

TMUS Global Solutions: TMUS Global Solutions is a world-class technology powerhouse accelerating the company's global digital transformation. With a culture built on growth, inclusivity, and global collaboration, the teams here drive innovation at scale, powered by bold thinking.

About the Role: As a Senior Engineer – Software Full Stack (API Gateway & AI Infrastructure), you will architect and deliver the platform software that runs T-Mobile's gateway and AI infrastructure layer — from developer-facing portals and operational dashboards to the control plane APIs, Kubernetes operators, and backend services that govern API Gateway, Istio, AI agents, Model Context Protocol (MCP) servers, and LLM gateways. You will own systems end to end, set technical direction for the team, raise the bar through code reviews and mentoring, and introduce architectural patterns that keep the platform scalable and operationally sound as AI workloads grow. Success is measured by platform reliability, developer adoption of self-service tooling, and the quality and velocity of the team's output. You will also apply AI coding tools, prompt engineering, and agentic patterns as a core part of your day-to-day SDLC — going beyond prototypes to production-grade use. We pride ourselves on encouraging a culture of innovation, agile ways of working, and transparency in all we do. Join us in embodying the spirit of the Un-carrier and make a tangible impact!

What You'll Do:

• Architect and implement full stack platform solutions for the API Gateway and Istio control plane — including developer portals, operational dashboards, and self-service UIs that let teams configure routes, traffic policies, and AuthPolicies without deep mesh expertise.
• Design and build backend control plane APIs, Kubernetes operators, and microservices that interface with API custom resources, Istio APIs, and Envoy xDS to automate gateway provisioning, certificate management, and policy lifecycle.
• Lead the engineering of AI gateway platform services — including MCP server registry and routing, LLM provider management (multi-provider failover, token-rate limiting, semantic caching), and AI agent ingress configuration — from design through production.
• Stand up new platform environments from scratch: front end build tooling, backend service scaffolding, Kubernetes manifests, Helm charts, and cloud infrastructure — setting the standard for how the team bootstraps new capabilities.
• Evaluate, recommend, and introduce cloud services and architectural patterns (event-driven, CQRS, operator pattern, GitOps) to improve scalability, observability, and operational safety of gateway and AI platform components.
• Design and manage data storage for gateway configuration state, traffic policy audit trails, AI usage metrics, and MCP tool catalogs — including performance tuning and refactoring across relational and non-relational stores as needs evolve.
• Implement and maintain CI/CD pipelines and GitOps workflows (Argo CD, Flux) for gateway configuration promotion and platform service deployments across environments.
• Apply test-driven development; maintain automated unit, integration, and regression test suites with high coverage in critical gateway and AI platform services.
• Troubleshoot production issues across the full stack — UI, control plane APIs, Kubernetes controllers, Envoy proxy behavior, and cloud infrastructure; conduct root cause analysis and implement corrective actions.
• Conduct peer code reviews and mentor engineers on gateway platform patterns, AI infrastructure design, Kubernetes API conventions, and secure-by-default development practices.
• Apply AI coding tools, prompt engineering, and agentic patterns as a core part of the SDLC — using them in production-grade workflows beyond prototypes (e.g., code generation, test generation, gateway config validation assistants, agentic task execution within engineering pipelines).
• Collaborate with SRE, security, and AI engineering teams to decompose features, define API contracts for gateway and AI services, and integrate platform solutions with enterprise systems.

What You'll Bring:

• Bachelor's degree in computer science, Engineering, or a related field; or an advanced degree with 3 years of related experience.
• Minimum 5 years of related work experience in software engineering.
• 5+ years of full stack web development experience, including front end and back end; significant experience building internal developer platforms, control planes, or operational tooling strongly preferred.
• Deep proficiency in React (or equivalent) and TypeScript/JavaScript for front end; Go, Python, or Node.js for backend services; ability to set up a complete full stack environment from scratch.
• Strong Kubernetes expertise: CRDs, controllers/operators, RBAC, admission webhooks, Helm chart authoring, and GitOps-based deployment patterns.
• Hands-on experience with Istio, Gloo, or another Envoy-based service mesh or API gateway; understanding of xDS APIs, VirtualServices, AuthPolicies, and traffic management at scale.
• Meaningful experience with AI gateway or LLM infrastructure: MCP protocol, LLM proxy routing and failover, token-rate limiting, semantic caching, or AI agent-to-agent communication patterns.
• 5+ years designing database schemas and writing SQL, with the ability to performance-tune and refactor across relational (PostgreSQL) and non-relational (time-series, document) stores.
• 3+ years using cloud services from AWS, Azure, or GCP.
• 2+ years of DevOps experience with infrastructure as code (Terraform, Pulumi, or similar).
• Demonstrated proficiency using AI coding tools, prompt engineering, and agentic patterns in real engineering workflows — applied in the SDLC beyond prototypes.
• Proven ability to perform code reviews, mentor peers, enforce coding standards, and drive architectural decisions across a team.
• Strong systems thinking: ability to evaluate interdependencies across gateway, AI platform, and cloud services; self-directed and motivated.

Must Have Skills:

• React (or equivalent) and TypeScript/JavaScript, HTML, and CSS for front end development.
• Backend service and microservice development in Go, Python, or Node.js.
• Kubernetes expertise: CRDs, operators, Helm, and GitOps-based deployments.
• API Gateway, Istio, or Envoy-based service mesh hands-on experience.
• AI gateway, MCP protocol, and LLM infrastructure platform knowledge.
• Database modeling, SQL, and performance tuning across relational and non-relational stores.
• Cloud services (AWS, Azure, or GCP) and infrastructure as code.
• CI/CD pipelines, GitOps workflows, and DevOps practices.
• Code review, mentoring, and architectural leadership.
• AI coding tools, prompt engineering, and agentic skill application in the SDLC (production-grade, beyond prototypes).