Amazon's Silk browser, used on the new Kindle Fire tablet, has raised concerns because it directs encrypted traffic through its EC2 cloud service and logs user data.
The opt-out feature directs SSL traffic through Amazon's web servers to speed up encrypted connections and page rendering which would otherwise be run on the device.
Amazon said in an FAQ that it did not collect personal user information but did temporarily store Kindle IP and MAC addresses, and an aggregate of websites that users visited for up to 30 days.
"Amazon's Silk optimises and accelerates the delivery of web content by using Amazon's cloud computing services.To do this, the content of web pages you visit using Amazon's Silk maybe cached to improve performance and certain web address information will be collected to help troubleshoot and diagnose Amazon Silk technical issues."
The company said security provided by websites "would still exist". It did not say if a certificate was created for the Kindle Fire.
Xamax Consultancy director Roger Clarke said the information on the Silk service from Amazon was confusing.
"It is confusing and perhaps should have been explained by technicians," Clarke said.
"But roughly speaking, it is a big concern in the broader vacuuming of data by the few big tech companies.:
He said the ability to offset processing requirements to the cloud was a clever use of technology.
"However we are concerned that privacy must be accommodated."
Clarke said Amazon's opt-out function was "nonsense" and should be made opt-in.