Spot.IM apparently started as a cross-platform chat application that web sites could add to their site. (For example, they have a Word Press plugin.) While looking at their web site, I noticed they have an unfortunate tendency to use the term "cross-site," which immediately makes me want to move the slider to "Do not trust." However, they actually mean cross-platform. The idea is you could join a chat hosted on a website on your laptop, continue it on your tablet via an app or browser and continue it even further on your phone (probably as a piece of the site's web app). While the presentation will vary, you won't lose context or chat messages.
A bit of digging on their main site ( http://www.spot.im ) seems to indicate that they've branched out to include a commenting system in addition to chat and some type of news feed tailored to (by?) each individual user.
Their LinkedIn page is at https://www.linkedin.com/company/spot-im , but frankly, it contains the most useless mission statement that I have come across on any Linked In page. It reads, "Spot.IM is a fast-growing startup with offices in New York City and Tel Aviv – and we’re hiring. Founders Nadav Shoval and Ishay Green launched Spot.IM in November of 2014. Through the consultation of over 300 global publishing experts, we have come to truly understand and empathize with the difficult problems of the online publishing industry faces. Spot.IM has undergone rapid change and immense growth as we attempt to find solutions for these problems, and what once began as an above-the-fold chat has evolved into a transformative, powerful social innovation for websites. As we emerge out of our Beta period for Spot 2.0, we have begun implementing our system with quite literally some of the biggest names in media. These industry leaders recognize Spot.IM’s technology is a unique opportunity to harness the power of their content."
You have to get several sentences in to get any idea of what it is they actually do - online chat - and even that is pretty vague. There is no mention of news feeds or commenting and the phrase "transformative, powerful social innovation for websites" sounds like marketing-speak and means absolutely nothing.
Their privacy police seem reasonable for what it is they do. Their opt-out is more or less "don't use our stuff," but you can also email them to ask for information to be removed.
I didn't get the sense they are doing cross-site tracking of individuals, but they sound like the do record PII of users on a specific site. They would probably have to in order to tailor a news feed for the user.