Yahoo! Search web services
Yahoo! introduced Representational State Transfer (REST) Application Program Interfaces (APIs) for web, image, local, news, and video search as well as Overture listings.
Yahoo! uses an application identifier (ID) and limits requests by Internet Protocol (IP) address. Service limits are set at 5000 requests per 24-hour period starting from the first time Yahoo! receives a call from the IP. This configuration allows for a developer to distribute his or her application without worrying about a user setting up their own API key. There could be issues on shared hosting setups where there are hundreds or thousands of domains sharing one IP address.
You may not use the Yahoo! APIs for commercial purposes. Yahoo! asks developers to use a special click Uniform Resource Locator (URL) they can track the use of their APIs.
True URL
https://www.niallkennedy.com/blog
Click URL
HyperText Transfer Protocol (HTTP)://rds.yahoo.com/S=96857362/K=niall+kennedy/v=2/XP=yws/SID=e/l=WS1/R=1/H=0/IPC=us/SHE=0/SIG=11k13a6du/EXP=1109747155/*-https%3A//www.niallkennedy.com/blog
Yahoo! does say please, but I see no reason for a developer to include the click URL in his or her application. Translating some parameters from the click URL above I am transmitting back to Yahoo! information that the user searched for “niall kennedy” (K) using the Yahoo! Web Services experience (XP) version 2 (v), the time the search took place (EXP) and more data not easily discerned.
The API response includes in its HTTP headers a Platform for Privacy Preferences Project (P3P) policy and an attempt to set a yahoo.com cookie.