Flight API Integration
Duffel API Integration Guide for Travel Developers
How to connect Duffel's airline and hotel API to build modern OTA and travel agency platforms
By Project OTA | 8 Aug, 2026 | 8 min read
Duffel provides a modern REST API for airline and accommodation booking. This guide covers the full integration flow from offer search to order management, plus how Duffel compares with GDS solutions.
What Duffel is and why developers use it
Duffel is a travel technology company that provides a single, modern REST API for booking flights, hotels and other travel products. For airline content specifically, Duffel acts as an NDC aggregator — it holds direct NDC connections and IATA accreditation with hundreds of airlines, and exposes all of this through a clean, well-documented JSON API. Developers building OTA portals, booking tools or travel apps can access multi-airline content without individually negotiating airline API credentials or managing GDS contracts.
Compared to traditional GDS integration, Duffel reduces time-to-market significantly. A developer can complete their first end-to-end test booking in hours rather than weeks, because Duffel handles authentication complexity, NDC schema differences and airline certification on the backend. The trade-off is that Duffel adds a per-booking fee and the developer operates through Duffel's commercial model rather than direct airline contracts.
Core Duffel API flow: OfferRequest to Order
The Duffel flight booking flow follows three main steps. First, create an OfferRequest — submit origin, destination, date and passenger details and Duffel returns a set of Offers from available airlines. Each Offer contains segments, cabin class, pricing, baggage allowances and available services such as seats and meals. Second, select an Offer and optionally retrieve a SeatMap for the selected flights, then bundle any ancillary services. Third, create an Order using the selected Offer ID, passenger details and payment information.
Post-booking, the Duffel API provides Order management endpoints for retrieval, cancellation and change requests. Each Order has a unique ID, the airline booking reference and the ticket numbers once issued. Webhooks are available for order status changes such as schedule changes, cancellations by the airline and refund completions, which lets your platform respond programmatically without polling.
Authentication, sandbox and production setup
Duffel uses token-based authentication — each API request requires a Bearer token included in the Authorization header. Duffel provides separate tokens for test mode and live mode. In test mode, bookings are simulated and no real airline reservations are created. This makes it safe to build and test the full booking flow before going live.
To move to production, Duffel requires account verification and agreement to their commercial terms. Depending on your business model and volume, Duffel may require additional identity or financial checks. API rate limits apply in both modes — your integration should implement retry logic with exponential backoff for 429 responses and circuit-breaker logic for persistent failures.
Integrating Duffel with your OTA platform
When integrating Duffel into an OTA booking engine, the search layer should call the OfferRequest endpoint asynchronously and stream or poll for results using Duffel's partial offers endpoint. This lets you display results as they arrive rather than waiting for all airlines to respond. Results from Duffel should be normalised into your internal offer model alongside GDS or other supplier content, keeping the booking logic supplier-agnostic.
For order management, store the Duffel Order ID and airline booking reference alongside the internal booking record. Cancellation and change requests must be routed back to Duffel via the Orders API. Duffel does not always support changes — availability depends on the airline and fare rules — so your UI should surface fare rule information clearly before purchase.
Duffel for hotels and stays
Beyond flights, Duffel's Stays API provides access to hotel and accommodation inventory through a similar REST interface. Developers can search availability, retrieve rate details, create bookings and manage cancellations using familiar Duffel patterns. The hotel integration is structurally parallel to the flight integration, which makes it efficient to extend an existing Duffel flight integration to cover accommodation without learning an entirely new API design.
For OTAs building multi-product platforms, this reduces integration complexity: one API key, one authentication model, one error handling convention and one settlement relationship covers both flights and hotels. However, Duffel's hotel inventory should be compared with dedicated hotel aggregators such as Hotelbeds, Ratehawk or Expedia Partner Solutions depending on your market's property coverage requirements.
Frequently Asked Questions
Does Duffel require IATA accreditation?
No. Duffel holds its own IATA accreditation. Agencies and developers access airline content through Duffel's commercial relationship, without needing their own BSP accreditation — though this may limit access to certain commercial airline programmes.
How does Duffel pricing work?
Duffel charges a per-segment or per-booking fee on top of the airline's net fare. The exact fee structure depends on your agreement and volume tier. Developers should factor this into their markup and pricing strategy.
Can I combine Duffel with GDS content in one booking engine?
Yes. Many OTA platforms use Duffel for NDC airline content and a GDS for legacy EDIFACT content, normalising both into a unified search results layer.
What airlines are available on Duffel?
Duffel connects to over 300 airlines including major carriers such as British Airways, Iberia, Vueling, American Airlines, Air France, Lufthansa and many low-cost carriers. Coverage varies by market.
Key Takeaways
- Duffel is a REST-based NDC aggregator — one API connects to 300+ airlines.
- The core flow is OfferRequest → Offer → Order, with seat maps and ancillaries available.
- Duffel handles airline credentials, NDC certification and BSP settlement on your behalf.
Project OTA builds Duffel API integrations for OTA platforms, agency portals and travel startups — covering full flight and hotel booking workflows with production-grade reliability.
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