Free Markdown tools
Small converters for getting things into Markdown. They run in your browser, so nothing you paste leaves the page, and there's nothing to sign up for.
Excel, Google Sheets or Numbers to a Markdown table
Paste cells or CSV, choose the alignment, and copy a GitHub Markdown table.
Google Docs, Word or Notion to Markdown
Paste formatted text and get headings, lists, links, tables and code as clean Markdown.
Both come from Coffee, a Markdown editor for Mac, iPhone and iPad. On the Mac, it does both of these when you paste into a note.