Ask HN: Markdown rendering on macOS Sierra

I fear this is a stupid/basic question to ask, but I'm eager to hear your input on this. I write documentation in Markdown for an open source project. I use Atom because it's marginally better than Coda for responsiveness and syntax highlighting. I know enough syntax/markup to get by, and I can check references for obscure stuff. The trouble is…I don't know how it looks until it's uploaded to GitHub and rendered there. I get a feel for it, but I don't have a specific Markdown to viewport rendering application. I realise there are _many_ applications that do this, but I'm interested in your Markdown workflow -- what do you use, and would you recommend it? Thank you in advance.