Senior Full-stack Developer

• Building features on the hotel contract and availability engine: seasons, rates, allotments, promotions and cancel rules
• Writing and maintaining supplier connections (SOAP and REST) and the partner API
• Building screens in our React back office for DMCs and tour operators
• Writing functional tests for every change and every bug fix
• Watching production in Datadog and fixing what breaks, with the rest of the team
• Reviewing merge requests, guiding design choices and keeping the code clean as the product grows

Problems you'll work on

• AI inside the platform.
• A key goal is to make Koob easier to use through AI. Our MCP server already lets AI agents search hotels, load contracts and book.
• Next come features such as RAG over our hotel and destination content, and assistants that help DMCs and tour operators get work done faster.
• Fast availability across suppliers. Room searches fan out to several hotel suppliers and our own contracts. We keep them fast with a shared Redis cache and an Elasticsearch read model that must stay in sync with PostgreSQL.
• A pricing engine with real rules. Seasons, weekday rules, promotions, extra beds and cancel rules all combine into one price, rounded to 2 decimals and identical on every path.
• Supplier connections. SOAP and REST integrations where each supplier shapes its data a little differently. We clean and check it where it enters the system.
• A versioned partner API. Three live API versions that partners depend on.
• Reliable background work. Imports, syncs and emails run as jobs on Cloud Tasks, with retries and alerts when they fail.

Must have

• Software design skills: you shape data models, API contracts and module boundaries that still hold a year later
• UI/UX design skills: we have no dedicated designer, so you design clear, usable screens yourself, from a rough idea to a finished page 5+ years building full stack web apps in production with TypeScript and Node.js or similar technologies
• Strong SQL
• Hands-on React experience
• You write tests without being asked
• Good written and spoken English: we work with international companies
• Able to work alone and ask for help early

Nice to have

• Experience building LLM features: MCP servers, RAG, embeddings, prompt design and evaluation
• Travel industry experience (hotel contracts, bed banks, GDS, channel managers)
• NestJS, an ORM such as MikroORM or TypeORM
• Elasticsearch knowledge
• Google Cloud, Terraform, Datadog