Senior Node.js Developer

About this role

⭐️ 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:

We build a high-load in-house platform for third-party integrations, real-time data processing, and reporting. We’re looking for a senior engineer who owns backend delivery and reliability, using coding agents as part of everyday development..

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Key Responsibilities

• Own backend changes from requirements and architecture through testing, deployment, and production support.
• Build and maintain backend services, APIs, and third-party integrations.
• Diagnose production issues and improve database performance, throughput, and observability.
• Use coding agents throughout delivery: define scope, provide context, set acceptance criteria, and verify results. Own the resulting code and its production behavior.
• Improve shared agent instructions, reusable skills, and automation to reduce repetitive engineering work.
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Requirements

• Strong production experience with Node.js and TypeScript, including asynchronous execution, concurrency, and performance debugging.
• Experience operating backend systems under load, with concrete examples of scaling improvements or incident resolution.
• Experience with MySQL, MongoDB, and Redis / Valkey, including schema design, indexing, query optimization, transactions, and caching strategies.
• Experience with message brokers such as NATS or Kafka, including delivery guarantees and idempotent processing.
• Practical experience shipping changes with Claude Code or comparable coding agents, with the ability to explain, review, and debug the resulting code.
• Ability to turn effective agent workflows into reusable team instructions, skills, and automation.
• Experience with automated testing, CI/CD, Docker, cloud infrastructure, and production monitoring.
• English sufficient for technical discussions and written documentation.
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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! ⭐