TheSage is a comprehensive dictionary and thesaurus that could become indispensable to writers of all sorts, including researchers, journalists, novelists, and students. The interface is slick and well designed, and the documentation is exhaustive. The program opens with a quick introduction, but it's a good idea to read the online documentation as well--TheSage is chock full of features, some of them a bit complicated to use.
The program uses Princeton University's WordNet, which is not a standard reference work. Perhaps as a consequence, TheSage is not very trustworthy when it comes to spelling: Searches on variants like "online" and "on-line" resulted in identical results, with no mention of preferred usage. Searches on British and American English versions of the same word also produced identical results, with no mention of variants. As a result, Professional editors may not find this tool terribly useful.
Searches provide your target word within definitions of other words; give you examples of use; return synonyms or homonyms; and many more options. TheSage offers wildcard searches that make is useful as a rhyming dictionary as well. You can search on terms in Wikipedia, Wiktionary, and Google with a built-in browser or your default. The program's browser worked great for the options provided, but when I clicked on a Google search result, it choked on a media-rich page and stalled the program. My computer locked up until the page loaded and I could close the tab. If you use an external browser, it opens up a Google page set to your search term.
This is a fairly complex program. For example, to find all words that rhyme with apple, I thought I could use the Phonetic Wildcard Search. When I entered "*ple" into that tool, however, I received zero results. I tried the same term using the main search bar and clicking the Wildcard button--and received 225 results. To be fair, the instructions say to read the documentation before using Phonetic Wildcard Search, and I didn't bother.
My criticisms need to be weighed against the fact that TheSage is completely free. It's a powerful dictionary and thesaurus program that offers many more features than similar programs I've seen. Writers who would appreciate help finding just the right word, and don't need to follow particular spelling standards, should give this program a try. If you find it useful--and I suspect you will--then please make a donation to support further development.