Amazon quietly launched a self-service tool to enable advertisers to engage their customers via cross-channel campaigns and extend campaign reach on and off Amazon. The tool, called Advertiser Audiences, will allow advertisers to anonymously match a list of their customers with Amazon shoppers and create new targeting segments for use in their Amazon advertising campaigns. Amazon, which announced the tool in a blog post, said studies showed that advertisers that created new audience segments using the tool experienced increased return on ad spend between 2x and 8x campaign averages. The tool is available for all advertisers, including those whose products or services aren’t sold on Amazon.com. To ensure customer privacy is protected, advertisers can either upload pre-hashed lists or have their lists hashed in their browser. Through this upload process, Amazon can never accept nor access any un-hashed data.