Last year, PDF search engines were just breaking ground on the Internet.  Back then, we were only able to find and review 3 PDF search engines—and all three were in beta. Needless to say, you couldn't be particular about your tools or your search habits when there wasn't much to choose from.

Fortunately, more than a year later, that has changed. Thanks to the continued development of online document management, essential tools, like document search engines, are gaining ground.

Now you can find more than just 3 PDF search engines.  Here are a few more that we reviewed to add to the list.