Senior Back End Developer Oeiras

Ko Start is an internet company focusing on highly competitive industry verticals. Our main markets include the United States, the United Kingdom, Italy, Spain, the Netherlands, Germany, Sweden, Australia, and Canada. We specialize in the creation and promotion of web and mobile projects, striving for excellence in all aspects of our work.

Role Description

The Senior Back End Developer role is a time, hybrid position located in Oeiras, with some flexibility for working from home. The Back End Developer will be responsible for designing, building, and maintaining side web applications. Day-to-day tasks include collaborating with mobile developers, product managers, writing efficient and secure code, integrating side logic with end elements, and ensuring high performance and responsiveness of applications.

Qualifications

• Strong discipline and management skills with a transparent workflow
• Strong experience with Nest
  JS, Type
  Script with real production experience
• Firebase Cloud Functions is a plus
• Confident in both backend (APIs, DB, integrations) and frontend (React or Next, CSS, Vanilla JS)
• Experience with Mongo
  DB, Postgre
  SQL, AWS/Google Cloud
• Understanding of cloud infrastructure and deployment processes
• Experience building scalable API search mechanisms and MCP server architectures
• Familiarity with LLM operations and AI-powered system integration
• Able to work independently, make technical decisions, and back them up with solid reasoning
• Extensive knowledge in backend optimization approaches
• Familiar with scaling mobile products with
  - side and optimizing performance
• Writes clean, maintainable code with tests
• Communicates well with both tech and
  - tech team members
• Proficiency in Object-Oriented Programming (OOP)
• Excellent
  - solving and communication skills
• Ability to work in a team and independently in a hybrid work environment
• Bachelor's degree in Computer Science, Engineering, or a related field is preferred