To capitalize all letters in various software applications, such as Microsoft Word, Google Docs, and Excel, users can use built-in tools or third-party apps like Zapier's Formatter tool. In Word, the easiest way to capitalize all letters is to highlight the text and click on the Change Case icon in the Home tab, or use the keyboard shortcut Shift + fn + F3 on Mac or Shift + F3 on Windows. Similarly, in Google Docs, users can access the Capitalization tool by clicking Format > Text > Capitalization. In Excel, functions like =UPPER, =LOWER, and =PROPER can be used to capitalize all letters. On a Mac, right-clicking on highlighted text allows users to select from various case options, including Make Upper Case and Make Lower Case. Sublime Text also includes a Convert Case tool, while web apps like TitleCase and Convert Case offer quick ways to change text case. Additionally, Zapier's Formatter tool can automatically capitalize all letters when sending information between apps.