You can use the command line tool cURL to send requests to the API.
curl -H "Connection: keep-alive" \
-H "Content-Length: XXX" \
-H "Cache-Control: no-cache" \
-H "Origin: XXXXXXXXXXXXX" \
-H "User-Agent: Provider User-Agent name" \
-H "Content-Type: text/xml;charset=UTF-8" \
-H "Accept: */*" \
-H "Accept-Encoding: gzip,deflate" \
-H "Authorization: Bearer {JWT}" \
--http1.1 \
-d @messagebody.xml -X POST \ 'https://(secure)-supply-xml.booking.com/hotels/{ota or xml}/{API name}'Here, {JWT} is the JWT Bearer token provided by Booking.com. For details on obtaining a JWT token, see Token-based authentication.
Replace the endpoint name according to the specification of the API to be called.