# Overview

**Seamlessly incorporate Booking.com inventory into your travel application.**

## Metasearch Connect API

Metasearch Connect API is dedicated for integration of metasearch engines. It's made compatible with [Demand API](/demand/docs/open-api/demand-api/) to simplify the transition for partners which currently use it.
Later, Metasearch Connect API will offer a new set of endpoints that are tailored for metasearch-specific use cases.

The transition will be performed in two phases:

1. During the phase 1, the changes you will have to make will be minimal: switching to a new API address and implementing a new token-based authentication mode. This however will require extensive monitoring on our end, therefore the process will be coordinated via account managers.
2. The phase 2 can require significantly more effort on your end, but it will not be purely a technical change. New
endpoints will also offer more features specific to metasearch engines, and extend to Booking.com's inventory in
other vertical sectors of the travel market (e.g. flights).


## Endpoints

The Connect API endpoints are grouped into two main collections (also referred to as APIs, for ease of reference).
Each API provides a different area of functionality.

### /demand-api-v3-compatible API layer

The /demand-api-v3-compatible API provides functionality specific to the accommodations sector of the travel market.
It is compatible with Demand-API v3. This is meant for easy transition in the short-term.

### /demand-api-v2-compatible API layer

This is compatible with Demand API v2, and is meant for easy transition in the short-term.

Note: All current endpoints exist for compatibility with demandapi and will be used only for transition. We suggest not to
migrate from `demand-api-v2-compatible` to `demand-api-v3-compatible`.
Around H2 2024, we will start adding new group of endpoints with a different interface, and we will ask all partners to
migrate to the latest version.

## Features

The Connect API is designed to provide flexible, scalable and expansible access to Booking.com inventory. For
compatibility, all the features in Demand API v2 which are being used by metasearch engine are also present in Connect API.

### Designed for future expansion

Currently, the Connect API offers access to Booking.com's property inventory:

* The /accommodations API provides *vertical-specific* functionality.
* The v2 compatible layer APIs are *vertical-agnostic*.


```mermaid
graph LR
    A(Partner app) --> B(/demand-api-v3-compatible)
    A(Partner app) --> C(/demand-api-v2-compatible)
```

Future versions of the Connect API will provide access to Booking.com's inventory in other vertical sectors of the travel market, by adding new, vertical-specific APIs, such as flights or car rentals. Each vertical-specific API will use a similar structure and design.

This will allow you to expand the reach of your existing application, by "bolting in" new, vertical-specific APIs according to your requirements, like this.

```mermaid
graph LR
    subgraph "Vertical Specific APIs (Future)"
    A(Partner app) --> B(Additional Vertical APIs)
    A(Partner app) --> C("Vertical 2 (e.g. Flights)")
    end
    subgraph "Vertical Specific APIs (Present)"
    A(Partner app) --> D(/demand-api-v3-compatible)
    end
    subgraph Vertical Agnostic APIs
    A(Partner app) --> E(/demand-api-v2-compatible)
    end
```