Silicon Valley Dictionary - Urban dictionary meets Silicon Valley
Grammarly - Clear, effective, mistake-free writing everywhere you type.
Writefull Thesaurus - A Google Docs add-on that uses AI to give you synonyms
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
Dictionary Anywhere - Dictionary Anywhere is an open-source and easy-to-use browser extension for Mozilla Firefox and Google Chrome that allows you to check definitions easily while browsing the web.
Typosaurus - Quickly check your website for spelling errors