Reblogging to save these resources for my own use, but also to add a few things as fic writer with English as a second language.
First of all - there are tons of us, don’t worry. :D
I’ll second NOT using google translate. Try taking a piece in your own language and run it back and forth through translate - it’s a great tool for getting the gist of an article or similar, but wholly unsuited for fiction IMHO.
I’ve never used grammary, but Microsoft Word has great tools for grammar and more - it can even warn you against passive voice. I would warn against Over Using these tools though. You want to find your own ‘voice’ when writing, and not make it sound like a generic piece of work. Again, fiction is not only about getting your point across in a concise manner (which many of these tools are aimed at), fiction is about the ebb and flow of the words. Sometimes you will do things that goes against grammar and clarity tools.
For words I don’t know I use a ‘define’ search rather than translate (aka search ‘define: subpar’ in you favorite search tool - but do set your locale to the locale you want to write as eg American or British (or any other) English).
Lastly, and most importantly:
Romance, fantasy, urban fantasy and sci-fi are often closest to Fanfic in terms of genre (fanfic is a specific genre with a specific style; fight me), but also read literary fiction. Read classics and modern works. Read books translated into English too - professional high quality translators usually do a fantastic job, and it always help to read diverse voices.
I’ve recently been reading The Hobbit aloud to my kids, and frankly it sparked my joy of the written word again, and my own writing. It’s been a while sine I read any Tolkien, and he does a couple of fun things with language - and many authors do this. Break rules and set rules and I find reading is the ONE thing that helps writing the most. Read, read and read some more.