Here's some tech style guides:

• Google developer documentation style guide
  • Word list
• Microsoft Writing Style Guide
• Red Hat Technical Writing Style Guide
  • Red Hat supplementary style guide for product documentation
• Bishop Fox Cybersecurity Style Guide
  • PDF
• Apple Style Guide
• Python docs style guide
• Canonical Documentation Style Guide
  • Canonical reStructuredText style guide

And some other style guides:

• Guardian and Observer style guide
• Wikipedia Manual of Style
• Mailchimp Content Style Guide
  • Writing for Accessibility
• and more

More on style guides:

• Write the Docs

Header photo: "Cootamundra Cycle Club, Cootamundra, New South Wales, c. 1900" by Mitchell Library, State Library of New South Wales, with no known copyright restrictions.