Which hotel PMS platforms have open APIs (and which are AI-ready)?

Apaleo is the cleanest answer to "which hotel PMS is genuinely open." It is built API-first, meaning the API is the product rather than an afterthought. According to Apaleo's developer documentation, getting started is as simple as "sign up for your apaleo developer account. It's free!" Access uses OAuth 2.0 (authorization code, client credentials, and refresh-token grants), and the core API spans "rates and reservations, accounting, housekeeping, inventory management, and payment."

Public integrations are published through the apaleo Store after a certification review, while custom client apps can be built for a single hotel without listing. The trade-off for that openness is scale: Apaleo is strongest with independents and boutique groups rather than large chains.

OPERA is the system most large and chain hotels actually run, and it is more open than its reputation suggests, with one catch: cost. Integration happens through the Oracle Hospitality Integration Platform (OHIP). According to Oracle, OHIP exposes "over 3,100 available operations" across reservations, front desk, guest profiles, distribution, housekeeping, and back-office cashiering, secured with "OAuth 2.0 based security plus individual application-key based access."

Partners self-register online rather than waiting for approval, but every call is metered. According to Oracle's OHIP datasheet, pricing "starts at $10 for up to 10,000 REST API transactions per month," billed monthly in arrears, with even sandbox usage billed. Publishing to the Oracle Hospitality Cloud Marketplace requires an Oracle PartnerNetwork membership; formal certification is optional.

Guesty is vacation-rental-first, but it earns its place here because it is used by serviced apartments, aparthotels, and hostels, and because it is the only platform in this scorecard with an official MCP server. According to Guesty's Open API documentation, access is self-serve: an account holder creates an application in the dashboard and authenticates with OAuth 2.0 client credentials. The API covers reservations, listings, calendars, guests, payments, financials, tasks, and messaging.

According to Guesty's MCP documentation, its MCP server "is currently in an early-stage beta release" and "exposes read endpoints only," connecting AI assistants including Claude Desktop, Cursor, and VS Code to live Guesty data. Guesty also publishes an llms.txt index. No hotel-native PMS in this review has matched that yet.

Cloudbeds pairs a broad API with the clearest AI-agent signal of any hotel-focused PMS short of a full MCP server. According to Cloudbeds' developer documentation, third-party apps need a Partner Dev Account that the Cloudbeds team enables, after which "API Keys Authentication is the recommended authentication method for all Marketplace partners," with OAuth 2.0 available as an alternative. A self-service API also lets an individual property generate its own credentials.

For AI builders, Cloudbeds' docs include a direct instruction: "For AI agents: visit https://developers.cloudbeds.com/llms.txt for an index of all pages formatted in Markdown and endpoints in OpenAPI." That is a deliberate, low-effort step toward agent-readiness that most peers have not taken.

Mews has one of the most approachable developer experiences in hotel tech, even though production is gated. Its Connector API documentation is fully public and ships with a shared demo environment, so you can make real calls before any agreement. According to Mews' Connector API documentation, authentication uses a token pair: a ClientToken identifies your application and an AccessToken identifies the property you are connecting to.

The API covers reservations, customers, rates, spaces, orders, and accounting. To move past the demo and connect real hotels, you complete the Mews certification process and list in the Mews Marketplace. No official MCP server or llms.txt is published yet, despite Mews' strong open-platform positioning, an obvious gap for them to close.

SiteMinder is a distribution platform (channel manager and booking engine) rather than a classic PMS, but it is core hotel infrastructure and it owns the small-property PMS Little Hotelier, so builders meet it constantly. Access is strictly partner-gated. According to SiteMinder's developer guide, "Access to SMX requires an active partnership agreement with SiteMinder," and "each API requires its own certification process," with most integrations completed within 60 days.

It is unusually forward on AI tooling for documentation: SiteMinder publishes an official llms.txt, a dedicated AI Tools page, and an agentic MCP path for its Channels Plus API. Note the scope, though, that tooling helps an AI read and reason over the docs and one distribution API, not operate a full PMS. Little Hotelier has no separate developer API of its own.