Senior Backend Developer

Summary

Join Holycode's Function 365 team as a Senior Backend Developer. Design, develop, and maintain large-scale applications and back-end systems using GraphQL, JavaScript, Node.js, and MySQL. Integrate with third-party APIs and write clean, well-documented, testable code. Participate in code reviews and guide junior developers. Implement testing, refactoring, and CI/CD processes. This role requires extensive experience with GraphQL and RESTful APIs, MySQL, JavaScript, and PHP, along with strong problem-solving skills and proficiency in Git. The ideal candidate will also possess knowledge of Symfony, AWS, and various software design principles. Function 365 offers a flexible work model, private health insurance, equipment of your choice, and opportunities for professional development.

Requirements

• Direct experience with GraphQL API design, implementation and upgrade
• Direct experience with RESTful API implementation, and upgrade
• 4+ years of relevant experience MySQL
• Strong knowledge of JavaScript and PHP
• Good knowledge of Symfony 6.x and MDB
• Experience with Relational DB
• Strong direct experience with integration of external API’s from other projects you’ve worked on
• Strong direct experience with developing internal API for internal and external consumption
• Knowledge of common accepted software design principles (design patterns, anti-patterns, refactoring, etc)
• Strong problem-solving and debugging skills
• Proficient with version control systems (Git)
• Good knowledge of Linux-like operating systems
• Knowledge of basic algorithms and data structures
• Knowledge of AWS
• Excellent/Fluent English level

Responsibilities

• Design, Develop and maintain GraphQL APIs for internal and external consumption
• Develop and maintain API integration of the F365 application with 3rd party API services
• Write clean, well-documented, and testable code using industry-standard coding practices
• Participate in code reviews and provide guidance to junior developers
• Implement tests (Unit, integration)
• Refactoring and bottleneck optimizing
• Participating in setting up CI/CD processes
• Implementing monitoring (Grafana)

Preferred Qualifications

• Experience with front-end testing frameworks (e.g., Jasmine, Karma) and back-end testing frameworks (e.g., Jest, Mocha)
• Knowledge of cloud platforms and deployment processes (e.g., AWS, Azure)
• Familiarity with agile methodologies and project management tools
• Familiarity with UI/UX design principles and accessibility standards
• Familiarity with front-end and back-end performance optimization techniques

Benefits

• Private health insurance
• Flexible work model – full remote or hybrid
• Equipment of your choice (laptop, monitor, accessories)
• High-growth company with innovative products
• Supportive, international team
• Budget for professional development (courses, books, conferences)
• English and German language lessons during working hours
• Nice office in Belgrade with a stocked kitchen and game area
• Opportunity to learn, grow, and make a real impact