I recently had an amazing writing experience using TeXstudio with a spell and grammar check done in real time (via Language Tool app installed locally). It is very useful if you are more focused on the subject and facts and less on the grammar and style. This is especially true if you are writing in some non-native language. Even simple checks like avoid word repetition and common typos not detected with speller are very helpful (a good example is “My English is very bed”). And this is not only about writing, a well-written text can provide a pleasure for a reader, a crappy one leads to annoyance.
There is a number of plugins aimed to do this for online writing. I am actually using one at the moment, however, it is a bit buggy on providing corrections for mistakes. The major drawback is that it is only for English.
Langage Tool is a Java app that can be run in server mode, and used via JSON API. Moreover, you can use your own instance (it is open sourced) or use the service they provide on web site. It has enough performance to check 400.000 sentences in about 4 minutes on my dual-core laptop, so it should not stack even under heavy traffic. As far as I know it is the best multilingual grammar checker, even more - it is relatively easy to contribute new rules for your native language to detect your favorable typos.
So, using a smart spell and grammar checker is a great pleasure, which can be provided to every Discourse post writer via integration with Language Tool (or any other app, probably you can find out a better possibility). Any ideas about implementation? Is it interesting enough to be added into Discource developers’ todo list?