SlipstreamJobs tracks this role from the company's public career site. Apply directly on the employer's site.
Salary: EUR 3,330 - 6,660 / monthly
KAYAK, part of Booking Holdings, is seeking a Senior Java Backend Engineer to join the K4B Directs team in Vilnius. This role focuses on designing, building, and owning direct supplier integrations that connect KAYAK for Business to airlines and travel suppliers, delivering content, fares, and services across search, booking, and servicing workflows.
You will lead the design and delivery of new direct supplier integrations from partner documentation through production rollout. Key responsibilities include owning the quality and reliability of live integrations by monitoring them, diagnosing production issues, and resolving gaps between supplier documentation and actual behavior. You'll evaluate user and business value before committing to build, track success metrics post-release, and build integrations with third-party APIs (SOAP/XML, REST, proprietary protocols), handling their quirks, rate limits, and failure modes.
The role requires designing for suppliers with widely differing protocols, data models, and reliability while maintaining a clean, consistent internal model. You'll act as a point of contact with partners on integration issues, investigating problems, agreeing on solutions, and following tickets through resolution. You'll contribute to technical decisions by writing design documents, reviewing architecture and code, and helping set standards for quality and testing.
Supporting mid-level and junior engineers is a core part of the role—through code reviews, pairing, and technical guidance. You'll collaborate with product, QA, and partner teams on scoping and rollout. AI coding tools are integrated into the team's workflow as a normal part of development.
The position requires working from the Vilnius office at least 3 days per week, with flexibility to work remotely up to 20 days per year.
REQUIREMENTS:
- Education in Computer Science or related field, or equivalent practical experience
- Significant hands-on experience with Java, including designing and operating production backend systems
- Strong experience with Spring framework and SQL databases
- Experience integrating with third-party systems and working directly with providers on communication, troubleshooting, and ticket escalation
- Experience 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 communication skills
- Comfort working hybrid with at least three office days per week
BONUS SKILLS:
- Experience with airline direct-connect or NDC APIs
- Knowledge of travel domain: fares, offers, orders, ancillaries, ticketing
- Experience with API certification or supplier testing programs
- Familiarity with AI coding tools and interest in using them to accelerate development
