Backend Developer | Senior

About the job

We are a cutting-edge ad-tech company: we process more than 4.5 million ad requests per second, replying under 100ms (for reference, the Google search engine handles ~76,000 QPS). Every day we generate several TBs of data that need to be processed, analyzed and aggregated, so our real-time components get smarter every day.

The Team

Core engineering team: 8 experienced engineers responsible for maintaining and evolving the real-time bidding (Open-RTB) auction system that powers the entire business. Fast-paced, supportive environment, knowledge sharing, autonomy.

What Will You Do

"You build it, you run it" philosophy — short-cycle tasks across the core platform, code reviews, technical/architectural decisions.

Key Responsibilities

• Feature Ownership: Design, develop and implement new features for core products using NodeJS and Java.


• Quality Assurance: Write clean, efficient, testable code; test locally and in a sophisticated staging environment.


• Operational Excellence: Monitor deployments, ensure stability, reliability and performance of production systems.


• Agile Collaboration: Participate in planning and progress reporting.

Requirements

• Bachelor's degree in Computer Science or related technical field.


• 5+ years of experience in a software engineering role.


• Hands-on experience with Java or NodeJS.


• Solid theoretical foundation in data structures, algorithms and software design principles.


• Genuine passion for technology, eagerness to learn.


• Excellent English (written and spoken).


• Proficiency with Linux, Git, Docker and Docker-Compose.


• Experience with testing tools and modern CI/CD frameworks.

Bonus Points

• Experience with Key-Value stores and in-memory databases (Redis, Memcached).


• Familiarity with cloud environments, particularly AWS.

Tech Stack

• Languages: Java, NodeJS, Bash, Python


• Databases: MySQL


• Cloud & DevOps: AWS, Jenkins, Docker


• Tools: Git, Jira, Notion

What They Offer

• Highly motivated, young and dynamic team.


• Great compensation package.


• Office in central Barcelona (rooftop terrace, BBQ, stocked fridge).


• Work-life balance: WFH 2 days/week, flexible hours.


• Meal vouchers (Ticket Restaurant).


• Monthly gym allowance (DiR or Wellhub).


• LinkedIn Learning and training opportunities.


• Monthly TGIF events, regular team-building.


• International team (40+ countries).

No visa sponsorship — candidates must already have a legal permit to work in Spain.