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Senior Backend Engineer: Recommendations (Remote)

Constructor

Spain Remote permanent

Posted: January 16, 2026

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Quick Summary

We're looking for a Senior Backend Engineer to join our team in Barcelona, Spain. The ideal candidate will have expertise in building scalable and efficient backend systems, with a strong understanding of machine learning and data structures. Key skills include proficiency in Python, experience with cloud-based infrastructure, and a passion for learning and innovating.

Job Description

About Us

Constructor is the next-generation platform for search and discovery in ecommerce, built to explicitly optimize for metrics like revenue, conversion rate, and profit. Our search engine is entirely invented in-house utilizing transformers and generative LLMs, and we use its core and personalization capabilities to power everything from search itself to recommendations to shopping agents. Engineering is by far our largest department, and we’ve built our proprietary engine to be the best on the market, having never lost an A/B test to a competitive technology. We’re passionate about maintaining this and work on the bleeding edge of AI to do so.

Out of necessity, our engine is built for extreme scale and powers over 1 billion queries every day across 150 languages and roughly 100 countries. It is used by some of the biggest ecommerce companies in the world like Sephora, Under Armour, and Petco.

We’re a passionate team who love solving problems and want to make our customers’ and coworkers’ lives better. We value empathy, openness, curiosity, continuous improvement, and are excited by metrics that matter. We believe that empowering everyone in a company to do what they do best can lead to great things.

Constructor is a U.S. based company that has been in the market since 2019. It was founded by Eli Finkelshteyn and Dan McCormick who still lead the company today.

About the Team

The Recommendations team plays an important role in improving the experience of our customers & end-users. We're a passionate team of cross-functional engineers who love challenges and want to make people’s lives better. We value openness, curiosity, continuous improvement, and great code. We believe that empowering everyone in a company to do what they think is best can lead to great things.

Our team is committed to perfecting traditional methods of product discovery while spearheading new avenues with the assistance of large language models, ushering in a new era of innovation and user engagement.

The Recommendation team manages multiple endpoints within shared services, alongside its own cloud-deployed solutions developed in Python, which require leveraging NoSQL databases and interfacing with both internal and external services. As part of our roadmap, we are planning to separate all main developments into distinct high-load distributed services.

About the job

A primary focus of this job is to design, deliver & maintain highload real-time web services in close collaboration with other great engineers both from recommendations & other teams.

• Build / deploy / support robust recommendations services including io-bound web services, cpu-bound services and data services
• Write AWS CloudFormation scripts, Jenkins jobs, Github actions following best industry standards
• Set up service observability, monitoring metrics, and alerting (Prometheus, Grafana, PagerDuty, AWS CloudWatch)
• Implement CI/CD pipelines and separate stability testing for recommendations needs
• Collaborate with technical and non-technical business partners to develop / update recommendations functionalities
• Communicate with stakeholders within and outside the team


Requirements:
• Strong computer science background & familiarity with networking principles

• Experience in designing, developing & maintaining highload real-time services
• Proficiency in Infrastructure as Code (IaC) tools like CloudFormation or Terraform for managing cloud resources.
• Hands-on experience with setting up and improving CI/CD pipelines
• Proficiency in a scripting language like Python and, as a plus, in compiled languages like Go or Rust.
• Experience in server-side coding for web services, and a good understanding of API design principles
• Skilled in setting up and managing observability tools like Prometheus, Grafana, and integrating alert systems like PagerDuty
• Familiarity with Service-Oriented Architecture, knowledge of communication protocols like protobuf
• Experience with NoSQL and relational databases, distributed systems, and caching solutions
• Experience with any of the major public cloud formation: AWS, Azure, GCP
• Experience collaborating in cross-functional teams
• Excellent English communication skills


Benefits:
• 🏝️ Unlimited vacation time - we strongly encourage all of our employees take at least 3 weeks per year
• 🌎 Fully remote team - choose where you live
• 🛋️ Work from home stipend! We want you to have the resources you need to set up your home office
• 💻 Apple laptops provided for new employees
• 🧑‍🎓 Training and development budget for every employee, refreshed each year
• 👪 Maternity & Paternity leave for qualified employees
• 🧠 Work with smart people who will help you grow and make a meaningful impact
• 💵 Base salary: $80k–$120k USD, depending on knowledge, skills, experience, and interview results
• 📈 Stock options - offered in addition to the base salary
• 🎉 Regular team offsites to connect and collaborate

Diversity, Equity, and Inclusion at Constructor

At Constructor.io we are committed to cultivating a work environment that is diverse, equitable, and inclusive. As an equal opportunity employer, we welcome individuals of all backgrounds and provide equal opportunities to all applicants regardless of their education, diversity of opinion, race, color, religion, gender, gender expression, sexual orientation, national origin, genetics, disability, age, veteran status or affiliation in any other protected group.

Studies have shown that women and people of color may be less likely to apply for jobs unless they meet every one of the qualifications listed. Our primary interest is in finding the best candidate for the job. We encourage you to apply even if you don’t meet all of our listed qualifications.

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