Senior Principal Software Engineer

Senior / Principal Software Engineer – C#, .NET Core & API IntegrationLocation: RemoteEmployment Type: Full-TimeAbout Us:AI-powered sales-intelligence platform that helps organizations identify,verify, and connect with their ideal customers through real-time data, buyer-intent insights,and intelligent automation. Our platform integrates AI, data science, and scalable backendsystems to deliver verified, actionable contact and company intelligence in seconds.We're expanding our engineering team with a Senior or Principal Software Engineer whowill lead backend architecture and third-party API integrations that power ZenBee'sintelligence engine. This is a high-impact, high-visibility technical leadership role within afast-moving AI startup.Role Overview:You'll own the design and implementation of secure, high-performance APIs and datasystems using C#, .NET Core, and SQL Server. You'll integrate multiple external dataproviders, ensure fault tolerance and recovery, optimize query performance, andcontinuously improve platform reliability and scalability.You'll collaborate with product and AI teams to ensure the data foundation behind ZenBee'sintelligence engine remains fast, accurate, and resilient.Key Responsibilities: Architect, develop, and optimize backend services using C#, .NET Core, and SQL Server. Lead third-party API integrations, ensuring security, scalability, and fault-tolerantrecovery mechanisms. Design and maintain RESTful and GraphQL APIs for internal and external systems. Build resilient retry, circuit breaker, and caching strategies for high-volume dataingestion. Implement API monitoring, observability, and telemetry to ensure uptime and dataaccuracy. Collaborate with AI engineers to enhance data pipelines and ensure seamless ingestioninto ZenBee's AI layer. Conduct design reviews, mentor developers, and contribute to ZenBee's engineeringstandards. Drive automation of testing, deployment, and infrastructure provisioning for allbackend components.Performance Metrics & KPIs:Your success will be measured by your ability to build reliable, scalable, and high-performing systems that directly impact ZenBee's platform quality and customerexperience. API Reliability / Uptime: ≥ 99.95% monthly uptime across all production services. Response Latency: Average API response time under 250ms for standard queries. Throughput Efficiency: Support sustained loads of 10K+ concurrent requests with nodegradation. Error Rate: Maintain critical API failure rate below 0.2% across integrations. Data Synchronization Speed: Reduce external API data sync latency to under 5 secondsper record batch. Release Velocity: Contribute to at least 2 major feature releases per quarter withmeasurable performance improvements. Technical Debt Reduction: Reduce incident or bug recurrence rate by >25% quarter-over-quarter. Code Quality: Maintain >90% unit test coverage and successful deployment on firstattempt in >95% of releases.Required Qualifications 10+ years of professional software engineering experience, including 5+ years in .NETCore and C#. Expert knowledge in API architecture, authentication (OAuth2/JWT), and performanceoptimization. Proven experience integrating complex third-party APIs and managing rate limits,retries, and schema evolution. Advanced skills in SQL Server (query tuning, indexing, partitioning, stored procedures). Solid understanding of multi-threading, asynchronous programming, and distributedsystem design. Experience with cloud platforms (Azure preferred; AWS or GCP acceptable) andcontainerized deployments (Docker, Kubernetes). Strong communication, leadership, and mentoring abilities.Preferred Skills: Experience with microservices and event-driven architectures. Familiarity with NoSQL, message queues, and caching systems (Redis, Kafka,RabbitMQ). Understanding of AI/ML data pipelines and real-time analytics. Exposure to CI/CD pipelines and infrastructure automation (GitHub Actions, AzureDevOps). Bachelor's or Master's degree in Computer Science or related field.Why Join Us:Help build one of the most intelligent, data-driven AI platforms for sales and recruitingprofessionals.Shape the technical foundation and architecture of a rapidly scaling SaaS product.Collaborate with a world-class, visionary team that blends AI, data science, and modernengineering.Competitive compensation, flexible work structure, and career growth opportunities.Make a measurable impact — every line of code directly influences how thousands ofbusinesses discover opportunities.Job Type: Full-timeWork Location: Remote