Full Stack Software Engineer I - Flights Ancillary Services Integration (ASI)

At Booking.com, data drives our decisions. Technology is at our core. And innovation is everywhere. But our company is more than datasets, lines of code, or A/B tests. We believe travel is a force for good in the world. Our mission is to make it easier for everyone to experience the world.

The Role

As a Full Stack Software Engineer (60% Frontend + 40% Backend) in the ASI team, you will own features end-to-end, from designing APIs and backend services to building interactive, high-performance front-end experiences used by millions of travelers. You will be part of a team that has full ownership of a critical business domain (ancillary products), working with a multidisciplinary team of backend and frontend engineers, product managers, UX designers, and data analysts.

You will work on some of the most complex and impactful areas in Flights, interactive seat maps, real-time pricing integrations with airline suppliers, post-booking upsell flows, and multi-supplier architecture. Every feature you build is validated through rigorous A/B testing, and you'll see the real-time impact of your work on millions of bookings.

Responsiblilities

• Build and maintain full-stack features across the ancillary booking funnel : seats, baggage, meals, and more

• Design and implement backend APIs (Java/Node.js) that integrate with airline suppliers and other aggregators

• Develop interactive, performant front-end components (React/TypeScript) - including complex UIs like seat maps and pricing displays

• Own the full experiment lifecycle - hypothesis, implementation, deployment, analysis, and iteration

• Collaborate with PM, UX, and data teams to translate business requirements into technical solutions

• Participate in on-call rotations and incident management for ancillary services

• Monitor and improve system reliability through SLOs, dashboards, and alerting

• Contribute to architectural decisions - API contracts, caching strategies, service boundaries

• Advocate best development practices within the team - code reviews, testing, documentation

Skills required

Must Have:

• Minimum 2-3 years of professional software development experience (excluding internships)

• Strong proficiency in at least one backend language - Java and Node.js preferred

• Working experience with Frontend Language - React and JavaScript/TypeScript

• Understanding of REST API design and service-oriented architecture

• Experience with relational databases (MySQL or similar)

• Experience with Git and modern development workflows

• Deployed at least one system in a cloud environment (AWS, GCP, or similar)

• Exposure to data-driven product development - A/B testing, metrics analysis, experiment-driven iteration

• Comfortable working across the full stack - not siloed into only FE or BE

Nice to Have:

• Experience with Kafka or other message streaming platforms

• Familiarity with gRPC/Protobuf

• Experience with Kubernetes and containerized deployments

• Experience with microservices architecture and distributed systems

• Familiarity with Cassandra or other NoSQL databases

• Travel/e-commerce/OTA domain experience

• Experience building complex interactive UIs (maps, data visualizations, real-time pricing)

• Exposure to monitoring tools (Grafana, Prometheus) and SLO-based reliability practices

what we Offer:

• Work on a high-scale, complex product - Flights processes millions of bookings, and ancillaries are a multi-million dollar revenue stream

• Direct business impact - every experiment you run has measurable revenue and UX outcomes

• Full ownership - from API design to production deployment; no waiting for other teams

• Rapid experimentation culture - ship fast, learn fast, iterate

• Strong engineering culture - code reviews, RFCs, architecture workshops, hackathons

• Opportunity to work on complex front-end challenges (interactive seat maps are "one of the most complex pieces of front-end we have")

• Collaborate with a diverse, international team spanning Bangalore, Amsterdam, and other locations

• Competitive compensation, benefits, and growth opportunities within Booking Holdings

Pre-Employment Screening

If your application is successful, your personal data may be used for a pre-employment screening check by a third party as permitted by applicable law. Depending on the vacancy and applicable law, a pre-employment screening may include employment history, education and other information (such as media information) that may be necessary for determining your qualifications and suitability for the position.