There have been so many occasions where I found a Web page that was frequently updated and what I really wanted was just the changed content so that I could mash it up and use the data in a different context.

Well, I found just the tool for the job: Feedity.

You give Feedity a URL and it figures out which sections of the page change and which don’t. It then removes the invariant parts and transforms the variable parts into RSS items and creates a feed! Incredibly clever and very effective.

Feedity retains all of the components of the “scraped” page so that links remain as links. Even better, if you don’t like what Feedity produces you can refine its translation and include link titles that should be in the generated feed and or define the starting and ending HTML blocks that you want to define feed items.

Feedity also supports the creation of “a data mashup ‘pipeline’ using Yahoo Pipes”.

Feedity is available under three subscription models which all provide “near real time” updating. The basic versions are the Free and Premium models (any donation amount qualifies for Premium service). Neither of these models commits to availability nor require registration and both have ads inserted into what is an RSS2.0 feed (for monetization).

The free model allows for no more than one hit per minute while the Premium version supports “low traffic” and a “fair usage policy.”

The Pro model offers a 99.9% uptime guarantee, is priced on application, requires registration, has no ads in the feed, and the feed can be formatted as XML, RSS, Atom, JSON, or CSV.

This service is actually more complex “under the hood” than it might appear and should provide and excellent platform for many mashups.

Mark Gibbs is a consultant, author, journalist, columnist and blogger.