google API help

all i need is the name of the API(s) - not the code, but if you have code C# i will pay for that also.
i am writing a webpage and i want to list businesses that are close to the user.
i need the list of businesses by either zipcode or by Lat, Lng
details in that list is the normal stuff for businesses, company name,address,phone,lat,lng,industry
if someone knows the answer and it takes 2 seconds- i will pay for full hour
thank you for you help in advance