Understand NDC vs GDS content differences as a travel API integrator

Steps

1. GDS (Global Distribution Systems: Amadeus, Sabre, Travelport) aggregate content from hundreds of airlines via EDIFACT-based protocols; NDC (New Distribution Capability) is IATA's XML standard allowing airlines to distribute rich, personalized content directly.
2. Many airlines now withhold their cheapest fares, bundles, and ancillaries from GDS and only distribute them via NDC channels — if your API only accesses GDS content, you may show higher prices than the airline's own website.
3. To access NDC content, you either connect directly to each airline's NDC API (requires certification and commercial agreements) or use an aggregator that has done this (Duffel, Verteil, TravelFusion, and others).
4. NDC responses are richer but less standardized than GDS — fields like baggage allowance, fare rules, and seat maps vary significantly in structure between airlines even within the NDC standard.
5. When aggregating both GDS and NDC content, deduplication is necessary — the same flight may appear as a GDS fare and an NDC fare with different prices, different ancillary inclusion, and different booking conditions.
6. Refund and change rules differ by channel: a ticket booked via NDC direct must typically be changed via the same NDC channel — cross-channel modifications (book NDC, change via GDS) are often not supported.