Hi Vikas,
Are you referring to retrieving search volume for keywords? In AdWords API,
TargetingIdeaService can be used to retrieve search volume data and trends for keywords. You need to set the TargetingIdeaSelector.requestType to STATS and select
TARGETED_MONTHLY_SEARCHES as one of the attributes to be returned in the response. You need to use the
RelatedToQuerySearchParameter to specify a list of seed keywords for which to retrieve the search volume data. You can also set other options to refine your results. This
guide provides more information on using TargetingIdeaService and also provides the mapping to Keyword Planner functions. The
GetKeywordIdeas PHP example demonstrates how to use this service.
Regards,
Shwetha, AdWords API Team.