You shouldn't run all your writing through it, though. Where I think this app shines is technical writing. If you want to describe a difficult concept to someone, you should make the explanation as simple as possible. That way, the reader will pay more attention to the concept than the prose.
Yes, I used it on this post.
I always found gender guessing algorithms to be a fun thing to play with as well, although I never used one in an attempt to make my writing more gendered one way or another. I just like to see which gender my various writing presents. And it does vary, depending on whether I am writing academic prose, fiction, poetry, etc. This is interesting at minimum as just another tool that allows/encourages/shows one how to play with writing.
I pasted my most recent blog in the gender guessing app. The app differentiates between formal and informal like this: Conclusion: I seem to go both ways. So true:Formal writing includes fiction and non-fiction stories, articles, and news reports. Informal writing includes blog and chat-room text. (Email can be formal, informal, or some combination.) You should view the results based on the appropriate type of writing.
The app defines blogs as a"informal", but I take a more formal narrative approach to my blog, so it could also be formal.Genre: Informal
Genre: Formal
Female = 487
Male = 734
Difference = 247; 60.11%
Verdict: MALE
Weak emphasis could indicate European. Female = 731
Male = 712
Difference = -19; 49.34%
Verdict: Weak FEMALE