Senior Software Engineer(Backend)

About OnArrival

OnArrival is building the infrastructure layer for modern travel distribution. We enable banks, fintech companies, loyalty platforms and consumer brands to offer flights, hotels, buses and travel services directly inside their own applications.

Our platform handles the complexity behind travel commerce, including supplier integrations, search, pricing, booking, payments, cancellations, rescheduling, reconciliation and post-booking support. We operate across APIs, SDKs and embedded user experiences, allowing our partners to launch travel products without building an entire travel stack themselves.

The Role

We are looking for a Backend Engineer who can build reliable, scalable and maintainable systems for a high-volume travel platform.

You will work on systems that process real customer searches, bookings and payments across multiple travel suppliers. This is not a role where you only implement isolated tickets. You will own services and workflows from design through production, monitor how they perform and improve them based on real-world usage.

You will work closely with product managers, frontend engineers, QA engineers, solution architects and external travel partners.

What You Will Work On

• Build backend services using Kotlin, Java and Spring Boot
• Design APIs for search, pricing, booking, payments, cancellations, rescheduling and refunds
• Integrate with airline, hotel, bus, payment and third-party travel APIs
• Build resilient workflows that handle supplier failures, timeouts, retries and partial transactions
• Design asynchronous systems using Kafka, SQS and event-driven architecture
• Work with MongoDB, Redis, PostgreSQL, Elasticsearch and ClickHouse
• Improve API response times, throughput, reliability and infrastructure efficiency
• Build configurable systems that support multiple enterprise customers and tenant-specific requirements
• Implement idempotency, distributed locking, caching, rate limiting and fault-tolerance patterns
• Write automated unit, integration and contract tests
• Own production releases, observability, alerts and incident resolution
• Investigate production issues using logs, metrics, traces and database analysis
• Participate in architecture discussions and technical design reviews
• Improve engineering standards, documentation and development tooling

AI-Native Engineering

At OnArrival, engineers are expected to use AI extensively as part of their everyday work.

You should be comfortable using AI coding and reasoning tools to:

• Accelerate implementation and code exploration
• Generate and improve automated tests
• Review pull requests and identify edge cases
• Understand unfamiliar services and large codebases
• Debug production issues and analyse logs
• Draft technical designs and documentation
• Automate repetitive engineering tasks
• Evaluate multiple implementation approaches before writing code

AI should improve your speed and quality, but you remain responsible for validating the output, protecting customer data and making sound engineering decisions.

What We Are Looking For

• 3 or more years of backend development experience
• Strong programming skills in Kotlin or Java
• Hands-on experience with Spring Boot
• Good understanding of REST APIs, HTTP, authentication and distributed systems
• Experience with relational or NoSQL databases
• Understanding of concurrency, transactions, caching and asynchronous processing
• Ability to write clean, testable and production-ready code
• Experience diagnosing performance and reliability issues
• Strong ownership mindset and comfort working in a fast-moving environment
• Ability to convert ambiguous business problems into well-designed technical solutions
• Comfortable using AI-assisted development tools as part of the software development lifecycle

Good to Have

• Experience with Kafka, Redis, MongoDB, Elasticsearch or ClickHouse
• Experience running services on AWS using ECS, EKS, Lambda, SQS, S3 or CloudFront
• Experience with observability platforms such as Grafana, OpenTelemetry, Datadog or SigNoz
• Experience building multi-tenant SaaS platforms
• Knowledge of microservices, event-driven architecture and distributed transaction patterns
• Experience with payment systems, booking systems or financial reconciliation
• Experience integrating with external APIs that have inconsistent behaviour or limited reliability
• Previous experience in travel technology, fintech, e-c…