Machine Learning Engineer

Sofia Stars is an operational services company based in Sofia. We offer a range of solutions for online businesses, including R&D, Marketing, Customer Support, KYC, Risk, and Anti-Fraud services. With 300+ bright stars on our team, we deliver secure, reliable solutions with a touch of quality that shines. When you join us, you’ll be part of a place where ideas light up, and growth isn’t just a promise—it’s a journey. 

❗️Please note that this role is office based for Sofia, Bulgaria (51, Blv. „Cherni Vrah“, Office „X“).

❗️If you need to be relocated, we take care of the process.

We are looking for a Founding Senior Machine Learning Engineer to join our team. As an early hire, you will work closely with the Head of AI to design, develop, and deploy AI and ML solutions from the ground up. This is a hands-on, high-visibility, and high-impact role that offers tremendous growth potential. You’ll play a pivotal role in shaping the technical foundation of our AI team and delivering real-world solutions in a dynamic, fast-paced environment.

✅ Responsibilities:

• Develop, train, and fine-tune Machine Learning and Deep Learning models for gaming and CRM use cases;
• Design, build, and maintain data pipelines to ensure reliable, clean, and scalable datasets;
• Collaborate with the Head of AI to transform prototypes into production-ready solutions;
• Contribute to infrastructure setup, including MLOps practices, and implement CI/CD pipelines for machine learning models;
• Work with cross-functional teams, including product and engineering, to integrate AI capabilities into customer-facing applications;
• Document and communicate results clearly, catering to both technical and non-technical stakeholders.

✅ Requirements:

• A minimum of 3+ years of experience in Machine Learning, Data Engineering, or Applied AI roles;
• Strong proficiency in Python and machine learning frameworks like PyTorch or TensorFlow;
• Solid experience with data engineering tools (e.g., SQL, Spark, Airflow, or equivalents);
• Hands-on experience with cloud platforms (AWS, GCP, or Azure);
• Proven expertise in deploying ML models in production environments;
• Strong problem-solving skills and the ability to work autonomously in a startup-like environment;
• Excellent communication skills in English.

✅ Nice-to-Have:

• Experience with MLOps tools such as Docker, Kubernetes, MLflow, or Weights & Biases;
• Familiarity with transformers and large language models (LLMs), particularly within the Hugging Face ecosystem;
• Exposure to a variety of data types, including structured (tabular) and unstructured (text, images).

✅ Why Sofia Stars?

💰 Competitive salary;

🍎 Monthly food vouchers (200 BGN);

💼 Official employment & Full medical insurance (including in-patient and out-patient care, maternity, dental, and annual health check-ups);

🌍 Working in a dynamic International company;

🌴 Up to 25 paid leave days;

🏥 Six additional days of undocumented sick leaves;

🎁 Birthday, wedding and newborn gifts;

⚽ Multisport card;

🧗‍♂️ Team-building events and activities;

🌆 Sunny, spacious office;

🍔 Food vouchers, breakfast, fruits, and snacks available in the office;

📈 Ability for career and professional growth within the company.

Ready to shine? Let’s make it real.

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