Senior Java Backend Developer – K4B Direct Integrations

About the role

KAYAK for Business (K4B) is building corporate travel technology, and its engineering team in Lithuania is growing. The Direct team connects K4B directly to airlines and other travel suppliers, delivering content, fares and services across search, booking and servicing. This role leads the design and delivery of new direct supplier integrations, owns the quality and reliability of live integrations and supports other engineers. At least 3 days per week must be spent in the Vilnius office.

Key responsibilities

• Lead the design and delivery of new direct supplier integrations, from reading partner documentation to production rollout.
• Own the quality and reliability of live integrations: monitor them, diagnose production issues and handle gaps between supplier documentation and real behaviour.
• Evaluate user and business value before building and track success metrics after release.
• Build and evolve integrations with third-party APIs (SOAP/XML, REST and proprietary protocols), handling quirks, rate limits and failure modes.
• Act as a point of contact with partners on integration issues, investigating problems and following tickets to resolution.
• Contribute to technical decisions: write design documents, review architecture and code, and help set quality and testing standards.
• Mentor mid-level and junior engineers through code reviews, pairing and technical guidance, and work with product, QA and partner teams on scoping and rollout.
• Use AI coding tools as part of the day-to-day workflow.

Required profile

• Education in Computer Science or a related field, or equivalent practical experience.
• Significant hands-on experience with Java, including designing and operating production backend systems.
• Strong experience integrating with third-party systems and onboarding new partners or suppliers onto an existing platform.
• Track record of leading projects end to end and supporting the growth of other engineers.
• Fluent English and comfort in a hybrid model with at least three office days per week.

Required skills

• Spring framework and SQL databases.
• Bonus: airline direct-connect or NDC APIs, knowledge of fares, offers and orders, ancillaries and ticketing, API certification or supplier testing programs, and familiarity with AI coding tools.

What we offer

• Salary of 3,330 to 6,660 EUR gross per month, plus significant yearly bonuses of about 10% of annual salary.
• RSUs (Restricted Stock Units) 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 and extra financial support for sick leave, plus a day off on your birthday.
• Annual company-wide vacation week, paid volunteering time, no-meeting Fridays and internal communities.
• Company-paid therapy sessions through SpringHealth and a HeadSpace subscription.