We are looking for a Senior Full Stack Engineer who is comfortable working on high-load, distributed systems and making architectural decisions, not just implementing tasks. At MMDSmart, you will work on a CPaaS/CCaaS platform handling messaging and voice communication at scale. This is not a typical CRUD product: you’ll deal with real-time flows, external integrations, billing complexity, and systems where design mistakes surface quickly in production. You will be expected to take ownership from design to delivery and challenge assumptions when needed. Since 2007, MMDSmart has been a leading supplier in cloud-based business communications , delivering game-changing IT products to businesses in over 100 countries. Our success is fueled by the inspiration and innovative ideas of our team members, encouraging their growth and impacting our Messaging and Voice solutions . These empower our clients to communicate more effectively with their customers. Don’t miss this chance to excel in a rapidly expanding tech company, where your potential and ambitions are not just recognized, but celebrated. Requirements What will you do at MMDSmart? Design and implement new platform capabilities across backend and frontend (not just “features” but system-level improvements); Contribute to architecture decisions in a microservices environment (Go-based services, event-driven patterns, APIs); Build and evolve React-based interfaces used by enterprise customers and internal teams; Work on integrations with external vendors (messaging providers, voice, billing systems); Investigate production issues in a high-scale environment and drive them to resolution—not just patch them; Participate in technical discussions, trade-off analysis, and system design reviews; Occasionally lead initiatives or own a domain end-to-end. You are a perfect match if you have: 4+ years of real production experience as a Full Stack Engineer; Strong backend expertise with Go (3+ years), not just syntax, but concurrency, performance, and system design; Solid frontend experience with React + TypeScript (2+ years); Experience building or maintaining distributed systems / microservices; Good understanding of data modeling (SQL + NoSQL) and when to use each; Ability to debug complex issues across services (not limited to your own code); Comfortable working in an environment where requirements evolve and not everything is predefined. Will be a plus: Experience with real-time systems, messaging, or telecom domains; Familiarity with event streaming (Kafka or similar); Experience with cloud platforms (GCP preferred); Exposure to billing systems or high-throughput APIs. What you get: Work on systems that actually operate at scale and have real business impact; A team where senior engineers are expected to influence architecture, not just execute; Remote work. Benefits 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.