What is "Fetch API Request?"

What is this thing I keep seeing in my log?

[gbelton]

When I look at my server logs, I keep finding these entries. There is no referer, they get my index page but none of the images or anything linked from that page, and the user agent says something like "Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.0) Fetch API Request".

They aren't normal web visitors, because they just take the index page and never anything else. They come from a bunch of different IP addresses. So what the heck is this?

[Air]

Welcome to wmw gbelton!

Looks like your question got lost in the shuffle for a bit, anyhow, that is likely an application using the Application Programming Interface of Win IE pulling pages specified for offline viewing by users. Tends to happen more on sites that offer frequently changing content, such as news sites, upcoming events, latest releases, etc ...

Could also be any other program installed by the user that uses the API to spider sites for ranking comparison, or some other unknown purpose.