Senior Full Stack Engineer, AI-First (Go / React)

We build cloud CPaaS/CCaaS infrastructure - the routing, messaging and real-time layer that contact centres run on. High traffic, event-driven services, and a UI that has to stay correct while thousands of live conversations move through it. We're hiring a senior engineer for a team where AI agents are part of the normal development loop, not a pilot. You'll own features end-to-end across a Go backend and a React/TypeScript frontend, and you'll be accountable for everything you ship — including the parts an agent wrote. This is not a prompt-engineering role. It's a senior engineering role where AI-assisted delivery is the default working method. What will you do at MMDSmart? Own features end-to-end across Go backend and React/TypeScript frontend; Design and develop solutions for high-load and distributed production systems; Use AI coding agents as an integral part of your everyday development workflow; Guide AI agents, review and verify their output, and take ownership of the final result; Build and evolve backend services, APIs, frontend functionality, and external integrations; Investigate complex production issues and drive them to resolution; Contribute to architecture decisions, technical discussions, and system improvements; Help improve our codebase and development practices to make AI-assisted engineering more effective. You are a perfect match if you have: 5+ years of professional software engineering experience and strong Senior-level engineering fundamentals; Strong hands-on production experience with Go - 4 years of experience; Practical experience with React and/or TypeScript; you don’t need to be a frontend expert, but you should be comfortable working with frontend code; Hands-on experience with high-load and distributed production systems; Experience designing, building, and debugging production services and APIs; Hands-on experience with AI coding tools such as Claude Code, Cursor, Windsurf, Copilot, or similar - beyond simple autocomplete; Ability to use AI to work effectively across different parts of the stack while critically reviewing and verifying its output; Strong engineering judgement, ownership, and ability to make technical decisions independently. Our Tech Stack: Backend: Go, microservices, REST APIs, GraphQL Frontend: React, TypeScript, Zustand / Redux Toolkit, WebSocket / SSE Event-driven: Kafka, NATS / JetStream, RabbitMQ, event-driven architecture Data: PostgreSQL, Redis, MongoDB Infrastructure: GCP, Kubernetes, Docker, CI/CD, Infrastructure as Code Observability & Performance: structured logging, metrics, tracing, profiling, high-load and concurrency tooling AI Development: Claude Code, Cursor, Windsurf, Copilot and other agentic development tools Domain: CPaaS / CCaaS, messaging, voice, real-time communication, external provider integrations Will be a plus: CCaaS / CPaaS / telecom background: contact-centre routing, ACD, omnichannel messaging. Voice stack: WebRTC, SIP, media servers, or CPaaS APIs API gateway and microservices integration; GraphQL federation. Kubernetes, Docker, CI/CD ownership, infrastructure-as-code. Polyglot persistence: Redis for caching and ephemeral state, PostgreSQL where a document model is the wrong fit; plus the judgement to tell the difference. MongoDB Atlas or self-managed cluster operations. Internal tooling, evals or automation built on LLM APIs. Open-source contributions, especially in Go. What you get: An AI-first engineering environment where AI is part of real production development; The opportunity to use AI to work across the full stack and expand beyond your primary expertise; Work on high-load communication products with real business impact; A team where Senior Engineers influence technical decisions and architecture; Remote work. Why do talents choose and stay at MMDSmart? Embrace the opportunity to work in a company that cares about: Your Wellness: Access to mental health programs, comprehensive medical insurance, and a sports card. Your Happiness: Enjoy the company of cool teammates, a friendly atmosphere, a strong mentorship, and a variety of bonuses & corporate gifts. Your Development: Benefit from free educational events & courses, and English classes with native speakers. Your Career: Focus on your professional development in a supportive environment. Work-Life Balance: Choose your working format - remote, office-based, or hybrid and engage in team-building activities. Think this role's got your name on it? Go ahead and apply, we'd love to see what you've got! Equal-Opportunity Employment We are an equal opportunity employer committed to creating a diverse and inclusive work environment. All qualified applicants will receive consideration for employment without regard to race, color, religion, gender, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. Medical Insurance and Sport Card perks are available for employees located in Bulgaria.