No such site does (or could) exist. While there are programs around that will flag syntax errors for you - such as warning you that you are missing a parenthesis or a comma, there is NOT a site that can check the logic of program. You can right a program that is syntax error free and it still fails because of a logic error - you have a math formula wrong, you pass the wrong parameter, or you condition fails so the programs loops the wrong number of times.
No web site can find those kinds of errors. How does the web site know that you intended to add "x+y+b" and not "x+y+z"? Or that you intended to loop "until" a condition rather than "while" a condition?
If you tell us the language you are planning to program in, we may be able to point you towards a site or a downloadable editor editor that can help you with specific language. But again, those usually can only find syntax errors, not logic ones.
Google - for certain things. It works better than iOS 8, per the link.
Otherwise, it's impossible. How can a website know what you meant ?
It doesn't happen at the website.
It happens in the program you're using. . . ie: your browser, MS WORD . . etc
