What are some alternatives?
When comparing Sharethrough and Contextly, you can also consider the following products
StackAdapt - Native advertising demand side platform.
Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.
Nativo - Nativo is an advertising technology platform for brand advertisers and publishers to scale, automate, and measure native ads
Pixfuture - Pixfuture is a self serve advertisement platform for advertisers and publishers.
Adobe Advertising Cloud - Adobe Advertising Cloud is ads providing a platform that lets your media-related thing to lift on the high note.
Digg - Digg delivers the most interesting and talked-about stories on the Web right now.