Job Information
Holycode Senior Backend (PHP) Developer - Classic Trader team in Belgrade, Serbia
Holycode is seeking an experienced Senior Backend Developer to join our Classic Trader engineering team and drive our technical evolution forward.
About Classic Trader
Classic Trader is Europe's largest online marketplace for classic vehicles, serving collectors and enthusiasts worldwide. Our platform features over 14,000 vehicle listings, attracts 6+ million monthly page views, and is complemented by our print magazine published six times annually.
About the Role
We're at an exciting inflection point—modernizing our backend infrastructure while scaling our platform. You'll play a pivotal role in leading our migration to contemporary technologies, reducing technical debt, and architecting solutions that serve millions of users. As a senior member of the team, you'll provide technical direction, mentor other developers, and make key architectural decisions.
What You'll Work On
Lead the migration of our backend stack from legacy systems (PHP 7.1, Symfony 2.8) to modern architecture
Drive technical decisions and define architectural standards for the team
Reduce technical debt and implement long-term architectural improvements
Optimize platform performance: improve API response times, database query efficiency, and overall system throughput
Profile and eliminate performance bottlenecks across the application stack
Design and build scalable APIs for our marketplace and CT Inspections product
Implement caching strategies and optimize resource utilization
Establish and improve testing practices (unit, integration, and end-to-end tests)
Streamline development workflows and improve team efficiency
Mentor and guide other developers through code reviews and knowledge sharing
Coordinate technical work and ensure code quality standards across the codebase
Scale infrastructure to handle increasing traffic and new product lines
What We're Looking For
Required:
6+ years of backend development experience with web applications and APIs
Strong expertise in PHP and Symfony framework (experience with both legacy and modern versions highly valued)
Proven track record in technical migrations and modernization projects
Demonstrated experience in performance optimization, profiling, and reducing API response times
Deep understanding of software architecture principles (SOLID, design patterns, clean code)
Production experience with relational and NoSQL databases, including query optimization
Experience with AWS, DevOps practices, and cloud infrastructure
Strong communication skills and ability to mentor other developers
Experience making architectural decisions and driving technical direction
Pragmatic approach to leveraging AI tools to enhance productivity and code quality
Focus on efficiency, automation, and streamlining development processes
Nice to Have:
Experience setting up and maintaining comprehensive test suites (PHPUnit, integration tests, etc.)
Familiarity with modern frontend frameworks (React, Vue, Angular, Svelte)
Experience with ElasticSearch, Redis, or similar technologies
Background in e-commerce or marketplace platforms
Experience with APM tools and performance monitoring solutions
Knowledge of CI/CD pipelines and automated testing workflows
Our Technology Stack
Current (in migration):
Backend: PHP 7.1, Symfony 2.8, MySQL, Redis, ElasticSearch
Frontend: Astro, Preact, Tailwind
Target: Modern PHP 8.x with Symfony 7+ (tbd) and cloud-native architecture
Why Join Us?
This is a rare opportunity to lead meaningful technical transformation at a well-established platform while working with a team that values craftsmanship, continuous improvement, and work-life balance. If you're passionate about clean architecture, enjoy solving complex migration challenges and performance optimization problems, leverage modern tools to work efficiently, and want to leave your mark on a product that serves a vibrant community, we'd love to hear from you.
Why you'll love working here:
Private health insurance
Flexible work model – hybrid or full remote
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
If you are looking for an environment where you can grow professionally, learn from the best in the field, balance work and life habits and have a pleasant and enthusiastic environment, please submit your CV in English.
Powered by JazzHR