Kien Nguyen Trung

Technical lead on a travel gateway platform — the layer that makes many hotel, flight, tour, transfer and car-hire suppliers answer one API contract.

• I run the release train as well as writing the code — promoting the shared integration branch to production across 8 gateway services, which means owning what goes out and when, not only what gets written.
• Decided white-labelling is a data problem, not a code problem — one integration resold under many brand codes through aliasing, with every per-brand difference pushed into data instead of forked code: around 150 live supplier codes across hotel, flight, tour, transfer and car hire running on roughly 90 integrations, mirrored between the search and the booking service.
• Decided against the big-bang engine cutover — suppliers migrated from the old engine generation to the new one with the system live, both generations serving production side by side.
• Ran the hotel identity mapping campaigns over a ~1.9M-row table: dry-run first, every written row re-read to verify, and one 11,953-row campaign rolled back when the team's evidence standard changed.
• Built the support tooling: from one trace-id, rebuild the exact runnable curl we sent upstream — shipped across all five products in a single day; and ported the Redis ops tooling to the two products that lacked it, adding the permission gate the existing implementations were missing.
• Packaged ~70 operational runbooks as executable commands installed from shared repos, so incident procedure stopped living in one engineer's head.
• Listed as one of three maintainers in the hotel search service's engineering documentation.

Designed the multi-level approval engine behind a corporate expense-management product — one public gateway class as the only way in, module boundaries enforced by lint, configuration snapshotted at submit so an in-flight request can never change its own rules — alongside flight and hotel booking microservices and a social network system.

• The engine's harder calls: optimistic locking on state transitions, a separate bulk path rather than a loop over the single-item path, and per-level SLA reminders on a delayed-job queue.
• Built the config-driven reporting and export layer: a different column set per enterprise customer — including fields with no database column at all — with no code change per customer.
• Delivered a flight-delay insurance product end-to-end across 11 repositories, then resolved two post-go-live production incidents with before/after verification on production rather than a claim of "fixed".

Built a Gateway Travel Booking System made of microservices for flights, hotels, tours, transfers and car hire. This is where the travel-distribution domain I still work in started.

• Chose a graph database for hotel identity — the same building carries a different ID at every supplier, and identity is transitive: if A matches B and B matches C, then A is C. That is a traversal, not a join, so the mapping system runs on Neo4j instead of the join table everyone reaches for.
• Planned, scheduled and implemented new supplier integrations into the system.
• Built and maintained the admin dashboard in ReactJS for managing products, suppliers and bookings.
• Built and maintained a log tracer for monitoring the system during incidents.

• First internship, overlapping my final year at HUST SoICT.
• Built a real-time comment system for a stock-market application — WebSocket for the live channel, RESTful APIs on the backend, and the comment UI on the frontend.