Short answer: there is no single best flight booking API. GDS APIs (Amadeus, Sabre, Travelport) give the widest traditional airline content but need accreditation or a consolidator to ticket. NDC connections give richer airline offers but one airline at a time. Consolidator and aggregator APIs are the fastest route to a bookable site for a new agency. Affiliate APIs pay a commission for redirecting traffic and need no ticketing at all.
The four families of flight booking API
Almost every flight API belongs to one of four groups. They differ less in technical shape than in where they sit in the distribution chain, which decides what content you see, what you pay and what paperwork you need.
1. Global distribution systems (GDS)
Amadeus, Sabre and Travelport are the three global distribution systems. They aggregate schedules, fares and availability from hundreds of airlines under long-standing distribution agreements and expose them to travel agents through terminals and APIs. Amadeus offers a Self-Service developer programme with REST APIs and a separate Enterprise tier for full production access; Sabre publishes its APIs through Sabre Dev Studio; Travelport exposes its content through JSON APIs on its Travelport+ platform. A GDS record (the PNR) is what airline, airport and back-office staff expect to see.
2. NDC direct connections
NDC (New Distribution Capability) is an IATA XML messaging standard that lets an airline sell its offers directly to a seller without the GDS in the middle. Airlines use it to distribute bundled fares, seat and bag offers and loyalty pricing they withhold from traditional channels. Connecting directly to an airline's NDC API is a per-airline project; in practice most sellers reach NDC content through an aggregator or through the GDSs' own NDC programmes.
3. Consolidator and aggregator APIs
This is the broadest and most varied family. A consolidator is an accredited ticketing agent that sells to sub-agents; an aggregator is a technology company that stitches together GDS, NDC, low-cost-carrier and sometimes other consolidator content into a single API. Examples our team has integration experience with include TBO and Tripjack (Indian B2B consolidators with wide domestic and international content), Mystifly (a global consolidator API), Duffel (a developer-first API with direct airline and NDC connections) and Kiwi.com's Tequila platform (a booking and affiliate platform, now available to approved partners by application rather than open sign-up). These APIs typically handle ticketing on your behalf, so the seller does not need IATA accreditation.
4. Affiliate and redirect APIs
Affiliate flight APIs, such as the ones offered through Travelpayouts, give you fare search data and deep links. The traveller searches on your site and completes the booking on the partner's site; you are paid a commission or a per-click amount. There is no ticketing, payment collection or customer service obligation for the booking itself. This is the model behind most flight affiliate sites; the flight affiliate website guide covers it in more depth.
Side-by-side comparison
| API family | Content coverage | Booking or redirect | Who can get access | Certification effort | Typical fit |
|---|---|---|---|---|---|
| GDS (Amadeus, Sabre, Travelport) | Widest full-service airline coverage; LCC coverage varies; NDC content via each GDS's own programme | Full booking and ticketing in your own PNR | Accredited agencies, or developers with a consolidator ticketing agreement | High: commercial contract, certification of your booking flows, compliance with the GDS's rules | Established agencies, corporate travel, B2B portals, high-volume OTAs |
| NDC direct (one airline at a time) | One airline's full retail offer including ancillaries and exclusive fares | Full booking, with order management handled by the airline | Sellers the airline approves, usually with existing ticketing capability | High per airline: each carrier has its own schema version, onboarding and testing | Agencies with strong volume on a few carriers; aggregators |
| Consolidator / aggregator API | Mixed: GDS, LCC, NDC and negotiated fares depending on the supplier | Full booking; the supplier issues the ticket | Registered travel businesses; sub-agent sign-up and a deposit or credit line are common | Low to medium: sandbox, sign-off of test cases, go-live review | New OTAs, white-label portals, B2B agent networks, campaign sites |
| Affiliate / redirect API | Broad search coverage via the partner's own metasearch data | Redirect only; booking happens on the partner site | Almost anyone with an approved website or app | Very low: account approval and API key | Content sites, price-comparison pages, startups validating demand |
Sources for programme terms: Amadeus for Developers documentation, Sabre Dev Studio, Travelport developer documentation, IATA NDC programme pages, Duffel documentation, Kiwi.com Tequila partner portal, Travelpayouts help centre. Terms change, so confirm the current conditions with each supplier.
Where each API sits between the airline and the traveller
The further right an API sits in the chain below, the less paperwork it needs and the less control you have over the fare, the ticket and the customer.
How flight API pricing models work
Suppliers rarely publish a simple price list, and quoted numbers change with volume and negotiation. What you can compare reliably is the shape of the pricing. Five models cover almost everything:
- Per-segment or per-booking fee. Common with GDS contracts and developer-first aggregators. You pay a fixed amount for each flight segment or each order created. Some suppliers add a small percentage of the order value on top. Duffel, for example, publishes a pay-as-you-go per-order price openly on its pricing page.
- Search-to-book ratio (look-to-book). Searches are free up to an agreed ratio of searches to bookings; beyond that each search is charged. Metasearch-style traffic with low conversion can become expensive under this model, so ask about it first if you expect a lot of browsing.
- Markup on net fares. The consolidator gives you a net fare and you add your own markup or service fee. Your margin is the difference. Most Indian B2B consolidator APIs work this way, often alongside a wallet or deposit you top up in advance.
- Commission or revenue share. Affiliate APIs pay you a share of the partner's revenue or a fixed amount per completed booking or per click. Rates are set by the network and the individual programme; check the current terms in the network's help centre rather than relying on figures quoted elsewhere.
- Platform or licence fee plus usage. Enterprise GDS agreements and some aggregator contracts combine a monthly or annual platform fee with usage charges and minimum volumes.
Two cost items sit outside the API price itself and are easy to miss: the integration and certification work needed to go live, and any deposit or credit line the supplier requires before it will issue tickets for you.
Access and certification: what each one asks of you
Broadly:
- GDS. Enterprise-level access comes with a commercial agreement and usually requires you to be an accredited agent (IATA, or ARC in the United States) or to work through a consolidator that is. Amadeus's Self-Service programme illustrates the pattern clearly: you can search and price freely in the test environment, but to move the booking API into production you must either be accredited to issue tickets yourself or hold a ticketing agreement with an airline consolidator, who then issues the ticket from the booking you create. The GDS integration page describes the technical work involved.
- NDC. Each airline decides who it connects. IATA retired its numbered NDC certification levels in favour of the Airline Retailing Maturity (ARM) index, which lists the verified capabilities of airlines, sellers and technology providers. A seller connecting directly should expect airline-by-airline onboarding and testing, and differing schema versions between carriers.
- Consolidator and aggregator APIs. You register as a business customer, sign an agreement, work in a sandbox, pass the supplier's test cases and get production keys. Indian B2B consolidators normally ask for business registration documents and a deposit or credit arrangement. Developer-first aggregators may let you self-serve into production with a card on file. Kiwi.com moved its Tequila platform to application-only access for approved partners, so do not assume every aggregator is open sign-up.
- Affiliate APIs. Approval of your website or app, acceptance of the programme terms and an API key. The main ongoing obligation is to keep your site compliant with the network's content rules.
Questions to ask before you choose
- Do we want to hold the ticket? If yes, you need a GDS, NDC or consolidator API and the obligations that come with it (refunds, schedule changes, customer support). If no, an affiliate API is simpler.
- Which routes and carriers matter most? Check real coverage for your top ten routes in the sandbox, including low-cost carriers, before signing anything.
- What is our expected search-to-book ratio? A metasearch or inspiration site will have a very different ratio from a B2B agent portal, and it changes which pricing model is affordable.
- Can we get production access at all? Ask the supplier directly what documents, accreditation, deposits and minimum volumes they require.
- How are post-booking changes handled? Cancellations, reissues, refunds and involuntary schedule changes are where support cost lives. Find out whether the API supports them or whether they go through email and a queue.
- Can we add a second supplier later? Most serious portals end up with more than one source. A booking engine that normalises results across suppliers makes that possible without rebuilding.
Which API suits startups, agencies and metasearch sites
A startup validating an idea usually does best with an affiliate API or a developer-first aggregator. Both can be live within weeks and neither needs accreditation. If the model depends on holding the booking, a consolidator API inside a white-label flight booking portal is the next step up.
An established agency that already issues tickets through a GDS should look at GDS APIs first, because its staff, back office and accounting already speak PNR. Adding NDC content through the GDS's own programme or an aggregator fills the gaps in airline content without a separate onboarding per carrier. Non-accredited agencies in India typically pair a GDS-backed consolidator API for international fares with an Indian B2B API for domestic content.
A metasearch site needs breadth of search content and a pricing model that tolerates a high search-to-book ratio, which points to affiliate and metasearch data feeds rather than ticketing APIs. Our flight API integration service covers all four families, and the travel API integration hub covers hotels, buses, transfers and insurance alongside flights.
This article is general information about travel technology and online marketing. It is not legal, tax or financial advice, and advertising platform policies change often. Check the current policy documents and take professional advice for your own situation.