MacDown

You can override this by going to the Security & Privacy pane in System Preferences. Click Open Anyway to authorize MacDown, or select the Anywhere radio button to allow all unidentified apps to open in the future. You may need to click the lock in the bottom left and enter your password first.

The developer had plans to build ports, and most of MacDown's core functionalities are based on C libraries, making it easier to replicate with other GUI frameworks. However, they currently lack the time to work on this but are open to sharing details if you're interested.

Yes, MacDown can be compatible with GFM by enabling specific options in the Markdown and Rendering preference panes. These include Tables, Fenced code blocks, Strikethrough, Autolink, and Task list syntax.

Yes, the developer accepts donations through PayPal. You can choose to tip them for a Coke, Beer, or Lunch, or even request a tweet. Donations are purely voluntary, and no specific benefits are provided in return.

You can report issues or suggest features on the project's GitHub issue page. For suggestions about the website rather than MacDown itself, you can report them separately. The developer also welcomes pull requests with implementations.

The developer does not currently promise API compatibility for macOS versions earlier than 10.8 due to limited resources. However, a cross-platform port might support older versions, as most cross-platform GUI frameworks go back to 10.6.

MacDown was initiated shortly after Apple announced Swift, but the developer felt Swift was not yet production-ready at the time. They expressed interest in using Swift in the future, however.

You can install MacDown via Homebrew Cask by running the command: brew install --cask macdown.