Liquid

Liquid is intended to increase your productivity when working with text. This application wonderfully integrates with your workflow, as it provides expedite access to such operations as searching the web, consulting reference sites, converting between units and translating text.

Once the initial configuration is done, which may get tricky for some users, the tool becomes a lot easier to use. Luckily, there is a video demonstration just in case you want to learn to use it more efficiently.

The application is very unobtrusive and runs from the Menu Bar. The workflow is quite simple, you just need to select the text you want to query, and then, pick the action you want to perform regarding your selection. Luckily, the tool integrates with Author and PDF reader applications. Likewise, it uses a set of keyboard shortcuts for faster access, which you can conveniently change in Preferences. Regrettably, you may find there are limitations as to setting your favorite reference sites.

In general, Liquid comes in very handy for those users, like writers, students and researchers, needing to consult Internet sources frequently. Luckily, the product is available from the Mac App Store at no cost. However, upgrading to the Pro version should be done via in-app purchase.