Software Engineer, Ads (Backend)

About the role

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:

- Design and build backend features, from scoping through deployment and ongoing production support, with guidance from senior engineers and tech leads on more complex or ambiguous problems

- Take part in technical design reviews and architecture discussions, asking good questions and contributing ideas

- Write well-tested, readable, and maintainable code consistent with team quality standards; participate actively in code reviews, both giving and receiving feedback

- Work with product managers and commercial partners to understand requirements and deliver reliable outcomes

- Participate in on-call rotations: monitor system health, investigate production issues, and write clear bug tickets and documentation

- Look for opportunities to improve system performance, reduce complexity, and pay down technical debt in aging codebases

- Take part in sprint ceremonies — planning, refinement, retrospectives, and demos — and contribute ideas for improving team delivery

- Use AI-assisted development tools responsibly to improve productivity, code quality, and delivery efficiency

- Collaborate with engineers, data scientists, and business intelligence teams to deliver integrated solutions

- Grow your skills through mentorship, pairing, and feedback from more senior engineers

Please apply if you have:

- Experience designing, building, and operating backend systems, gained through professional roles, internships, or substantial personal or academic projects

- Working proficiency in Java or a comparable backend language

- A foundational understanding of system design and debugging, and comfort working in distributed or 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 learn new tools, systems, and approaches, and to challenge existing approaches with well-reasoned alternatives

You may also bring (not required — equivalent experience, training, or transferable skills considered):