In 2004, subtel was established in Berlin to address the shortage of quality replacement batteries no longer provided by original brands. Today, under the CELLONIC label, we serve 13 countries with premium batteries that extend device service life, cut spending and protect the environment.
Your mission
- Maintain and optimize our high-traffic Hyvä store (v1.3.5) by identifying performance bottlenecks across our 50+ custom modules, leveraging Varnish, Elasticsearch, and Cloudinary CDN optimizations
- Deliver new customer-facing features via lean, well-structured Magento modules for FAQ, self-service, payments and localisation
- Set up and support A / B and multivariate tests in VWO so Product and Marketing can base decisions on clean data
- Apply AI tools in your workflow and evaluate fresh AI services that could enhance search, merchandising or support
- Work hand-in-hand with CTO and Product Manager, bringing in external specialists when deeper expertise is required
Technical environment
- Architecture : Enterprise Magento 2.4.x with Hyvä Theme, Magewire components, Tailwind CSS
- Integrations : Custom ERP, Adyen payments, Cloudinary CDN, DeepL AI, Intercom, Google Analytics 4
- Performance stack : Varnish FPC, Elasticsearch, Redis, custom MviewMaintainer for index optimization
- Testing : PHPUnit, Cypress E2E, PHPStan level 5, custom email testing framework
- Deployment : Multi-store setup with 9 languages (13 countries), Amazon S3 media storage
Framework
- Long-term freelance contract, minimum 30 hours per week, fully remote
- Six-month roadmap already defined; 50-person company with quick decisions
- Working with established codebase of 50+ custom modules in production
Your profile
- 5+ years Magento 2, including at least one live Hyvä project (ideally v1.3+)
- Enterprise module development experience with PSR-4 autoloading, dependency injection, and service contracts
- Performance optimization track record with Varnish, FPC, database indexing, and CDN implementations
- Integration experience with payment gateways (Adyen preferred), ERP systems, and third-party APIs
- Testing discipline with PHPUnit, integration tests, and automated testing tools
- VWO or similar A / B testing platform integration experience
- AI implementation experience beyond basic usage - API integrations, workflow automation
- Weekday availability 08 : 00–13 : 00 CET; fluent English (German welcome)
Interested in the Senior Magento 2 Developer role? Apply today and we’ll get back to you within 72 hours.