Here are some useful Add-ons that you can use within Google Docs™.
To install an Add-on, go to the Add-ons menu and click “Get Add-ons”.
This useful plugin allows you to highlight words from a word list in a Google Spreadsheet™. You can highlight from a word list, highlight a selection, highlight continuously as you type, and highlight sentences by length. It also has functions to clear highlights from the entire doc or a selection. It also includes a stats viewer for word count, word frequency, lists of all the sentences, and readability statistics. The help file is here.
While you can get some synonyms from Google’s thesaurus by selecting a word, right-clicking it, and choosing “Define”, it’s not comprehensive.
OneLook Thesaurus provides standard synonyms, rhymes, and frequently used words that often appear near the word you are looking up.
This plugin generates a word cloud from your source material. This can be very useful to understand the frequency of occurrence of the words in your document, or just to share word clouds with friends. The word clouds are generated as transparent-background .png files, you can can copy-and-paste them into any website or social app.
This simple tool allows you to get a word and character count, but exclude certain sections of the document, such as headers or titles.
First written as a demo app by Google to highlight the extensibility of Google Docs™, this app has useful tools for quick and easy translations.
For some reason that has been lost to time, screenplays are still put in an archaic manuscript format, despite the fact that no one has written a screenplay on a typewriter in twenty years. However, if you are writing a screenplay, you must play by the rules. This add-on will help you do that.