The Mailchimp Content Style Guide is a free, public company style guide (Creative Commons licensed) covering grammar, mechanics and tone: emphasizes clear, human, adaptable content, plain language and accessible/translatable writing.
Free and publicly licensed (Creative Commons Attribution-NonCommercial 4.0): adaptable by other organizations.
Content teams building or refining their own house style guide who want a proven, publicly-shared example rather than starting from a blank document.
Being Creative Commons licensed means teams can legally adapt sections of it directly into their own internal style guide, a genuine head start rather than just inspiration to paraphrase.
Mailchimp's own writing principles and content guidelines.
