Middle + Backend Developer

Company & Product

Mercaux is an in-store B2B SaaS Platform that aims to transform offline retail and help traditional retailers smoothly transition into the digital era. Founded by Harvard Business School alumni and ex-Yandex tech team, Mercaux’s products are live in 40 countries including the UK, Italy, Spain, US, Canada, and Thailand.

Mercaux’s Next Generation Platform is comprised of In-Store Experience, Universal Basket, and Next Generation Checkout layers, to help retailers provide customers with a frictionless omnichannel shopping experience. The solutions are operated by Sales Associates using the Mercaux App via a tablet or iPhone-based device, or self-served by customers using their own phones (via a web-based App) or touch screen kiosks/Digital Fitting Rooms. All the solutions are managed by a SaaS HQ Platform.

Retailers such as Nike, Stadium Goods & Springfield typically see a sales uplift in-store and 5x ROI, in a matter of months.

Mercaux has an international team in multiple offices - London and Barcelona.

Job & Location

Mercaux has an international team in multiple offices - London and Barcelona, as well as a remote team.

Who we are looking for and why:
We are looking for a Middle + BackEnd developer (in Serbia, or remote) to optimize our AWS services, boost scalability, and build a strong base for advanced analytics and machine learning, with a possible move to Azure.

At Mercaux, our backend is a collection of cloud-based RESTful API services built on the reliable Java (and a tiny bit of Kotlin) + Spring + Hibernate stack. One standout feature for us is our multi-tenancy approach, where all Mercaux clients coexist within a single infrastructure.

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From a business perspective, these services handle user authentication, rights management, data storage and retrieval, message forwarding through the Twilio API, integration with OMS, and much more. We're seeking a skilled backend developer who can help scale out our platform's core (e.g., preparing for potential sharding) and drive the development of new business scenarios.

What you will need to do:

- Developing and maintaining a suite of AWS-based services (with potential expansion to Azure in the future)
- Enhancing scalability and identifying performance bottlenecks
- Building the foundation for advanced analytics using statistical and machine learning techniques
- Collaborating closely on optimising memory and CPU utilisation, as well as fine-tuning complex SQL queries

How to know if you’re the right fit:

- You've worked with similar infrastructure: Linux, PostgreSQL, AWS (SQS, SNS, S3, CloudFront)
- You possess solid Java skills: Hibernate, Spring, Spring Boot
- You're well-versed in SQL: optimising complex queries, memory and CPU usage, etc.
- You're experienced with development tools: CI/CD deployment (Teamcity), bash, gitflow
- You have familiarity or hands-on experience with: AWS ECS, EC2, ASG, RDS, Lambda, Docker, Load testing (Jmeter)
- You can effectively communicate in English for work purposes, especially in written form
- You're hands-on, take full ownership of your work, and value accountability from start to finish

What we offer:

- International, diverse, and dynamic team
- Opportunity to create something new, and to transform the retail industry
- Competitive salary
- Health Insurance (upon probation)
- Paid time-off + applicable local public holidays
- Hybrid workplace (with the office in Barcelona or Serbia)