Senior JAVA Software Engineer, Ads

KAYAK, part of Booking Holdings (NASDAQ: BKNG), is a leading travel search engine. With billions of queries across our platforms, we help people find their perfect flight, stay, rental car and vacation package. We’re also transforming business travel with a new corporate travel solution, KAYAK for Business. As an employee of KAYAK, you will be part of a travel company that operates a portfolio of global metasearch brands including momondo, Cheapflights and HotelsCombined, among others. From start-up to industry leader, innovation is in our DNA and every employee has an opportunity to make their mark. Our focus is on building the best travel search engine to make it easier for everyone to experience the world. IN THIS ROLE YOU WILL: - Lead the design and delivery of complex backend features, from initial scoping through deployment and ongoing production support - Contribute to technical design reviews and architecture discussions, collaborating with engineers and architects across teams - Write well-tested, readable, and maintainable code consistent with team quality standards; participate actively in code reviews and provide constructive feedback - Mentor and support the growth of less-experienced engineers through technical guidance, knowledge sharing, and pairing - Work closely with product managers and commercial partners to clarify requirements, surface trade-offs, and deliver reliable outcomes - Participate in on-call rotations: monitor system health, investigate production issues, and write clear bug tickets and documentation - Proactively identify opportunities to improve system performance, reduce complexity, and address technical debt in aging codebases - Contribute to sprint ceremonies — planning, refinement, retrospectives, and demos — and help improve team delivery processes over time - Use AI-assisted development tools responsibly to improve productivity, code quality, and delivery efficiency - Collaborate across engineering, data science, and business intelligence teams to deliver integrated solutions PLEASE APPLY IF YOU HAVE: - Demonstrated experience designing, building, and operating backend systems in production environments - Strong proficiency in Java or a comparable backend language, with comfort working across distributed systems and service integrations - Experience with system design, performance optimization, and debugging in complex, multi-service environments - A collaborative working style: you communicate clearly, follow through on commitments, surface risks early, and ask good questions - Professional proficiency in written and spoken English - Curiosity and a willingness to challenge existing approaches with concrete, well-reasoned alternatives You may also bring (not required — equivalent experience, training, or transferable skills considered): - Familiarity with ad tech systems, bidding logic, or monetization infrastructure - Experience with server-to-server data integrations or event-driven architectures - Experience working in an agile team environment with sprint-based delivery - Comfort with observability tooling, metrics, and production debugging workflows A specific degree is not required. We welcome candidates from non-traditional educational backgrounds who demonstrate strong engineering fundamentals and a track record of delivering quality software. COMPENSATION: salary consists of three elements: Base pay: from 3330 EUR up to 6660 EUR gross monthly. In addition: - Significant yearly bonuses, approx 10 percent of annual salary. - Booking Holdings RSU (Restricted Stock Units) package, worth 20000 USD gross, with possibility to receive yearly refreshes.   BENEFITS: - Work from (almost) anywhere for up to 20 days per year - Funds for your career growth - Access to thousands of on-demand e-learnings - Generous additional Health Insurance - Flexible sick time off - Additional financial support for your sick leave - Additional day off on your birthday - Company-wide vacation week once a year (winter holidays) - Additional financial support during parental leave - Free lunch twice a week and daily snacks at the office - Free yoga twice a week - Paid volunteering time - No meeting Fridays - Office and team events such as summer camp, KAYAK birthday, winter party and more! - Company-paid therapy sessions through SpringHealth - Company-paid subscription to HeadSpace - Internal Communities   INCLUSION At KAYAK, we want everyone to have the space to grow, share ideas and do great work. That’s why we’re focused on hiring the best talent from all walks of life and experiences, supporting them well and making sure no one feels like they have to fit a mold to belong here. If you need accommodations during the application or interview process, or on the job, we’re here to support you. Please reach out to your recruiter to request any accommodations.     #LI-MP1