What Is the OpenTravel Alliance (OTA XML)?

The OpenTravel Alliance is a not-for-profit trade association that publishes OTA XML, a schema of standard messages travel companies use to exchange data. Booking.com and Google, for example, take inventory, property content and rate updates as OpenTravel messages on some of their endpoints. The "OTA" in OTA XML stands for OpenTravel Alliance (OpenTravel Alliance, Wikipedia) (Connectivity APIs documentation (overview), Booking.com Developers) (ARI rate (OTA_HotelRateAmountNotifRQ), Google Hotel Prices XML reference).

Last updated: November 2026

How OpenTravel Alliance messages work

Each OTA XML message is named for the job it does. Booking.com's connectivity endpoints carry the standard names, such as OTA_HotelInvNotif and OTA_HotelProductNotif (Connectivity APIs documentation (overview), Booking.com Developers). Google's hotel price feed sends rates in OTA_HotelRateAmountNotifRQ, the root element for a rates message (ARI rate (OTA_HotelRateAmountNotifRQ), Google Hotel Prices XML reference).

A message also declares which version of the standard it follows. Google's rate message uses the OpenTravel 2003/05 namespace, carries an OpenTravel message version field and reports problems with OpenTravel error codes (ARI rate (OTA_HotelRateAmountNotifRQ), Google Hotel Prices XML reference).

Releases are named by year and letter. OpenTravel 1.0, the XML line, runs from 2001A to its latest release, 2024A, while OpenTravel 2.0 was last released as 2019A (Download Specs, OpenTravel Alliance).

A channel picks the release it supports and can add its own schema where the standard stops. The Booking.com Connectivity APIs use OTA version 2003B, and Booking.com uses its own B.XML schema to fill in functions OTA cannot support (Connectivity APIs documentation (overview), Booking.com Developers).

The receiving side also sets its own limits. Google supports up to three years of rate data and up to 5,000 room-and-package products per property, and recommends keeping rate messages under 5 MB at no more than 400 files per second (ARI rate (OTA_HotelRateAmountNotifRQ), Google Hotel Prices XML reference).

Two connections can both be OTA XML and still differ in release, extensions and limits. A property's software has to match each channel's version of the standard, which is why connecting to a new channel takes setup work even when both sides speak OpenTravel.

Why it matters for hotel distribution

The standard comes from a body that spans travel. OpenTravel's members include airlines, hotel companies, car rental companies, cruise lines and railways (OpenTravel Alliance, Wikipedia). A hotel's rate message is built on the same family of schemas as the messages other travel sectors exchange.

Hotel content is a growing part of that work. The 2019A OpenTravel 2.0 release focused mainly on hospitality, with messages for pushing and requesting full or partial hotel content (OpenTravel 2019A Object Suite Available for Public Review, OpenTravel Alliance). Those hotel content messages are published in both XML and JSON and support the use cases in HEDNA's 2018 Content Whitepaper (OpenTravel Alliance Releases 2019A Object Model Publication Featuring Hospitality Enhancements, Hospitality Net).

The XML line keeps growing too. A newer OpenTravel 1.0 release adds hotel data fields for accessibility, sustainability, and health and safety measures (Key enhancements for hoteliers with OpenTravel 1.0 update, AHLA). For a property, details a guest asks about before booking, such as an accessible room, gain a standard place in the message instead of a free-text note.

The format has moved as well: the shift from XML to JSON has been treated as a syntax change, and OpenTravel 2.0 takes a model-driven approach (OpenTravel Alliance home page).

OTA XML compared with OpenTravel 2.0 and proprietary channel schemas

 OTA 1.0 XMLOpenTravel 2.0Proprietary channel schema
FormatXMLJSON and XMLSet by the channel
Releases2001A to 2024A2016A to 2019ASet by the channel
Published byOpenTravelOpenTravelThe channel itself, for example Booking.com B.XML
Hotel use in the sourcesChannel messages for inventory, product data and ratesPushing and requesting hotel contentFunctions OTA does not cover

Standards bodies have worked on overlap between these formats. In 2017 an HTNG workgroup with OpenTravel and IATA reviewed hotel distribution messaging, including OpenTravel 2.0, HTNG Lightweight Messaging and IATA NDC, and called for the three groups to collaborate to reduce duplicate standards (Recommendations Released for Future of Hotel Distribution Connectivity Standards, OpenTravel Alliance).

Frequently asked questions

Does OTA in OTA XML mean online travel agency?
No. In OTA XML, OTA is short for OpenTravel Alliance, the body that developed the XML schema. Online travel agencies are among the channels that receive these messages, which is why the two meanings get mixed up. A message whose name starts with OTA_, such as OTA_HotelInvNotif or OTA_HotelRateAmountNotifRQ, is an OpenTravel message, whichever system sends or receives it.
Is the OTA XML schema free to download?
The specifications are downloaded from the OpenTravel website after accepting a non-exclusive license. The license lets a company use and modify the documentation to build its own products, but not change the specification or create a new standard from it. The download page asks companies that derive value from the files to donate toward costs and does not state a price.
When was the OpenTravel Alliance founded?
The OpenTravel Alliance was founded in 1999 by a consortium of travel companies. Version 1 of its specification was first released for public review in February 2000, and the oldest release still listed for download is 2001A. That long history is one reason a hotel connection can run on a release from the early 2000s and still be in daily use.
Who leads OpenTravel hotel message development today?
By 2019, OpenTravel had moved its association management to HTNG (Hospitality Technology Next Generation), a non-profit founded in 2002. HTNG leads hospitality message development by managing workgroups and defining requirements. The newer OpenTravel 1.0 release with accessibility and sustainability fields was published jointly by HTNG, HEDNA and OpenTravel, so hotel requirements reach the standard through those groups.
Does OpenTravel 2.0 replace OTA 1.0 XML?
No. OpenTravel 2.0, announced in March 2016, added JSON messaging to the existing XML capabilities. Both lines are still offered for download, and the 1.0 XML line has had newer releases than 2.0 since 2019. A property or its software provider can meet either, depending on what each channel supports.

Related terms

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Where Jetstream fits

OpenTravel messages are how many of a property's channel connections carry rooms, rates and content. Jetstream builds an AI channel manager that connects a property's systems to the channels where guests book and keeps rooms, rates and availability accurate on each one, managed from one place.

See Jetstream's AI channel manager Book a demo