SFDocs Markdown Assistant–Provides palette commands and shortcuts that make it easy to write Markdown.
Prettier–Enforces a consistent style by parsing your code and reprinting it with its own style rules.
Vale-Provides customizable spelling, style, and grammar checking for a variety of markup formats (Markdown, AsciiDoc, reStructuredText, HTML, and DITA)
Code Spell Checker-help catch common spelling errors while keeping the number of false positives low.
LTeX+-provides offline grammar checking of various markup languages in Visual Studio Code using LanguageTool (LT)
ESLint-Lints JavaScript and TypeScript code to enforce consistent style and catch common errors.