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