Markdown → reStructuredText

reStructuredText is the format of Python documentation: Sphinx, Read the Docs and much of the language ecosystem expect .rst files. Anyone writing Markdown day to day who needs to contribute to one of those projects ends up translating the markup — and the differences start right at the headings, which in RST use no hash marks but a line of symbols underneath the text.

Paste the Markdown and the page returns the RST equivalent. The three heading levels get underlined with equals, hyphen and tilde, sized to the length of the title; list items swap the hyphen for an asterisk; strong emphasis becomes a double asterisk, which is the same on both sides; and a fenced code block becomes the double-colon marker followed by an indented block, which is how RST represents literal code.

The conversion works line by line and covers what appears in most of a README. What it leaves out is anything requiring an understanding of the whole document — tables, footnotes, cross-references, Sphinx directives. For a large file the result serves as a first pass; for a full project migration, the usual tool is Pandoc, which builds the document tree before writing.