Senior Node.js Developer

⭐️ CoreStar is a dynamic technology company supporting partners in heavy-load industries with high-performance solutions. Our expert teams bring a startup-driven mindset, focusing on innovation, collaboration, and efficiency in every project. At CoreStar, you’ll have the opportunity to grow your skills, tackle exciting challenges, and directly contribute to impactful products.

📌 Project:

High-load in-house platform handling multiple third-party integrations, data collection, and comprehensive reporting systems. The system processes large volumes of real-time data and requires high availability with performance optimization.

📌 Key Responsibilities:

- Develop scalable backend systems - design and implement high-load applications capable of handling massive traffic with optimal performance

- Build robust APIs and microservices - create RESTful services, GraphQL APIs, and real-time WebSocket connections for complex distributed systems

- Optimize application performance - identify bottlenecks, implement caching strategies, and ensure optimal resource utilization in production environments

- Design and implement third-party integrations - connect external APIs, payment systems, and various service providers while maintaining system reliability

- Develop from concept to production - participate in the full development lifecycle, from initial architecture design through deployment and monitoring

📌 AI-Assisted Development

- Deliver with agents as a normal way of working - break work down so that a meaningful part of it can be handed to agents, and use them daily rather than occasionally

- Contribute to shared AI tooling - write and improve reusable skills, commands and automation that the rest of the team uses, instead of keeping your workflow private

- Automate repetitive engineering work - identify what should not be done by hand any more and remove it

📌 Technical Excellence

- Ensure code quality and maintainability - write clean, well-documented code following best practices and design patterns

- Monitor and troubleshoot production systems - investigate complex issues, optimize database queries, and maintain system stability

- Collaborate with cross-functional teams - work closely with product managers, designers, and other developers to deliver high-quality solutions

- Stay current with technology trends - continuously learn and evaluate new tools, frameworks, and best practices in the Node.js ecosystem

📌 Requirements:

- 5+ years of professional software development experience with a strong focus on backend systems

- 4+ years of hands-on Node.js development in production environments with deep understanding of JavaScript runtime internals

- 3+ years of experience with high-load systems - building applications that serve large user bases with high availability requirements

- Proven track record of performance optimization - experience with scaling applications, database optimization, and system architecture

📌 Technical Skills

- Advanced JavaScript and TypeScript proficiency - ES6 +, async/await, promises, and TypeScript for large-scale applications

- Node.js ecosystem mastery - Express.js, Fastify, or similar frameworks with deep understanding of event loop and performance optimization

- API development expertise - RESTful services, GraphQL implementation, WebSocket connections, and third-party API integrations

- Database optimization - MySQL , MongoDB, Redis / Valkey with advanced query optimization, indexing strategies, and schema design

- Message queuing and streaming - NATS or Apache Kafka for building distributed, event-driven architectures

- Monitoring and observability - Prometheus, Grafana, ELK stack for comprehensive system monitoring and debugging

- Containerization and orchestration - Docker for development and deployment, Kubernetes for production scaling

- Cloud platform proficiency - AWS or Azure services with experience in auto-scaling, load balancing, and distributed systems

📌 AI Engineering

- Hands-on experience with agentic development tools - Claude Code or equivalent, used as part of daily delivery

- Experience creating reusable AI tooling - skills, commands, agent workflows or MCP integrations that other people also use

- Verification discipline - treats model output as something to be checked before it is acted on

📌 Additional Qualifications

- Strong English communication skills - ability to participate in technical discussions and document complex systems

- Performance-focused mindset - deep understanding of scalability principles, caching strategies, and optimization techniques

- Problem-solving expertise - capacity to debug complex distributed systems and design elegant solutions for challenging technical problems

- AI-ready mindset - actively looks for work that can be moved from people to agents, and adapts how they work as the tooling changes

📌 Benefits:
🏝 24 working days of paid annual leave 
🤝 6 days of paid sick leave  
🖊 Official employment
📄 Medical insurance
☕️ Coffee zone with fruit & snacks available in the office 
🥗 Corporate Lunch provided by the company
💪 Gym and sports classes 
🙌 Healthy and friendly work atmosphere  
📚 Greek and English language classes (partially covered)

Join us and be one of the Core Stars! ⭐