Senior Java Software Engineer, Ads

About the role

KAYAK, part of Booking Holdings, is a travel search engine and is hiring a Senior Java Software Engineer for its Ads team in Kaunas. You will lead the design and delivery of complex backend features, from scoping through deployment and production support, and mentor less-experienced engineers.

Key responsibilities

• Lead the design and delivery of complex backend features, from initial scoping through deployment and ongoing production support.
• Take part in technical design reviews and architecture discussions with engineers and architects across teams.
• Write well-tested, readable and maintainable code, take part in code reviews and give constructive feedback.
• Mentor and support less-experienced engineers through technical guidance, knowledge sharing and pairing.
• Work with product managers and commercial partners to clarify requirements, surface trade-offs and deliver reliable outcomes.
• Join on-call rotations: monitor system health, investigate production issues and write clear bug tickets and documentation.
• Identify opportunities to improve performance, reduce complexity and tackle technical debt in aging codebases.
• Contribute to sprint ceremonies (planning, refinement, retrospectives, demos) and help improve team delivery processes.
• Use AI-assisted development tools responsibly and collaborate with data science and business intelligence teams.

Required profile

• Demonstrated experience designing, building and operating backend systems in production.
• Strong proficiency in Java or a comparable backend language, with comfort across distributed systems and service integrations.
• Experience with system design, performance optimization and debugging in complex, multi-service environments.
• Clear communication, proactive risk surfacing and curiosity about challenging existing approaches.
• Professional written and spoken English.
• No specific degree required; equivalent experience, training or transferable skills are considered.

Required skills

• Java or a comparable backend language
• System design and performance optimization
• Optional but valued: ad tech systems, bidding logic or monetization infrastructure, server-to-server data integrations, event-driven architectures, agile sprint delivery, observability tooling and production debugging workflows

What we offer

• Base pay of 3,330 to 6,660 EUR gross per month, plus a yearly bonus of around 10% of annual salary.
• RSUs worth 20,000 USD gross, with possible yearly refreshes.
• Work from almost anywhere for up to 20 days per year, free lunch twice a week and daily snacks.
• Health insurance, flexible sick time, extra sick leave support, a day off on your birthday, a company-wide winter holiday week, paid volunteering time and no-meeting Fridays.
• Career growth funds, on-demand e-learning, yoga twice a week, paid therapy sessions and subscriptions to HeadSpace.