Kurzweil Education has a full-fledged assistive technology suite for students with dyslexia and other learning challenges. It's got text-to-speech support in 13 languages, speech-to-text dictation, and dyslexic fonts. It also integrates with Google Classroom and other learning management systems, so it's good for in-class and out-of-class use.
Another option is ParagraphAI, an AI-based writing assistant that helps with fluency, grammar, spelling and style. It supports more than 40 languages and can translate text, so it's good for people who have language barriers. It's available on mobile devices and as a web app, so you can use it anywhere to make sure your writing is good.
If you're looking for something more language-agnostic, LanguageTool offers an AI-based language checker and paraphrasing tool in more than 30 languages. It's got grammar checking, tone suggestions and paraphrasing. Plugins for popular writing tools and browser extensions let you use it for personal and professional writing.
Last, Grammarly offers personalized advice and text generation to help you write better and faster. It's got contextual suggestions, plagiarism detection and citation support, and it works on all devices. There are several plans to match your needs, so Grammarly is a good option if you want to improve writing clarity and consistency.