Every time an AI hands you a .md or .html file, you need somewhere to open it. Porthole is that app.
Lightweight viewer + editor for Markdown and HTML — GitHub-flavored rendering, syntax highlighting, live split-view preview. Set it as your default and AI-generated files route there automatically.
Free, open source. macOS + Windows.
Note: macOS will show a security prompt on first launch — right-click and select Open.
