How can I export Markdown documentation to different formats?
For choice of output formats, you probably can't beat pandoc - it will convert Markdown (and many other formats) into HTML, PDF, DocBook, and a number more. Its defaults are fairly sane, but you can include your own templates easily enough if you wish. It also has support for language-specific code highlighting in blocks.
The following letters are to denote some common features:
M: Mathematical formula syntax support
G: GitHub Flavoured Markdown
L: Live Preview
C: Syntax highlighting for code
E: Export to various formats
S: Custom Styling i.e custom CSS for HTML, etc.
P: Support for plugins
F: Free
D: Active development
Here they come (in no specific order):
1. Remarkable
Simple, elegant, feature-rich
D F L G S P M C E(pdf, html)
2. ReText
Simple, supports both restructured text and markdown
D F M P E(html, odt, pdf)
3. UberWriter
Minimal and lightweight
F C M E(pdf html rtf)
5. Typora
Simple, elegant
F(while in beta) D G C M L E(html pdf epub docx odt etc.)
6. Haroopad
Feature-rich, beta editor for blogging and mailing, import many formats
F G L M E(html)
7. Mark My Words
Simple
F D L E(pdf html)
8. Gitbook Editor
For documentation, digital writing and publishing
D F G L C M E (HTML PDF epub mobi)
9. Abricotine
Editor based on web technology
L F D G C E(HTML) M S
10. GhostWriter
Simple, distraction-free, robust
F G D E (HTML , other formats by extensions), S
11. Caret
Minimal, robust
D L G C E (PDF) M S
13. Elegant Markdown Editor (EME)
Minimal, simple
D L G C E (PDF) M
14. Plugins
The following are plugins available for various IDEs and editors. Some have plugins to convert to HTML or PDF. Check them out.
Atom
Vim: Instant-Markdown Plugin
Bracket: MarkdownPreview Plugin
Sublime Text: Markdown Plugin
GNU Emacs
Visual Studio Code
Notepadqq
Jetbrains IDEs: Markdown Navigator
Qownnotes
Just to complement the previous answers:
I found this online Markdown-to-PDF converter. But there are some downsides to using online services. Not only can they taint the PDF (free lunch?), but they also won't incorporate local images into your document.
Here's an offline Markdown-to-PDF converter called Gimli, but it runs on Ruby.
There's also another offline converter MultiMarkdown to PDF, but it uses Windows instead.