(This is close to some previous questions, but I wasn't able to find a question that directly covers it.)
I want a program that allows me to quickly type a snippet of LaTeX code in and will immediately give me feedback (an image) of the typeset output produced by the code.
If the program takes too long to start up or needs secondary programs to assess the results (image viewer or pdf reader), it frustrates use as a quick check of code.
An implementation of what I want is the Math Overflow question section. If I type LaTeX code, I see the results of the code immediately.
The purpose might be to quickly verify my LaTeX. I wouldn't want this to write a whole article just a few lines of code or text.
Thanks for any advice.
Edit: I am on Windows. Sorry for the crucial omission.