This is a short list – there are many more resources online.

Purdue OWL – Purdue University’s Online Writing Lab contains many comprehensive handouts on writing processes, citing sources, grammar, and more

Excelsior OWL – Excelsior College’s Online Writing Lab is geared toward academic writing but has good sections on grammar, citing sources, and the writing process, all relevant to technical writing

Empire State College’s Writing Resources – includes sections on grammar, punctuation, and ESL/ELL resources

About Writing: A Guide – an open educational resource (OER) textbook that includes sections on grammar and English as a Second Language challenges

Technical Writing Toolbox – a blog that links to other blogs and useful resources, including writing and grammar tips

Free Technical Writing Courses – a Technical Writing blog that links to a YouTube channel and many other blogs, links, and websites