Which files Resomark opens

Markdown, plain text, code and configuration files can be edited in Resomark. PDFs, images, web pages, Office and iWork documents, audio and video open right in the app for viewing, but can't be changed. Resomark doesn't open archives, installers, apps and similar files; it hands them to other apps.

• Markdown: .md, .markdown, .mdown, .mkd, .mdx. Formatting shows as you write, and the line with the cursor shows the source. .mdx is formatted as Markdown; the JSX inside isn't run.
• Plain text, code, scripts and configuration: .txt, .log, source files in many programming languages, .json, .yaml, .csv, and files recognized by name such as Dockerfile, .gitignore and .env. They're shown in a monospaced font with syntax highlighting and line numbers.
• HTML: shown in Web Preview by default; click Web Preview in the toolbar to switch to the source and edit it. See below.

Text files that aren't UTF-8 open in their original encoding, and when you save, the encoding and line endings stay as they were.

• PDF: zoom, find, and swipe left and right to turn pages. In Dark Mode, a toolbar button inverts the pages to dark.
• Images: can be zoomed when opened on their own.
• Web pages (HTML): HTML files open in Web Preview by default, which shows the page in a restricted environment. A page with no web addresses in its source can read the files in its Workspace (or, outside any Workspace, in its own folder), except files and folders whose names start with ., and has no network access except Google Fonts. A page with web addresses in its source can use the network but can't read your files; images and styles in its folder are only displayed. When a page wants more than that, a notice at the top says "This page wants to load content from the internet. Load it only if you trust this page." Click Load Content to allow it, for this opening only. To open HTML files as source first, turn off Open HTML files in Web Preview in Settings > Editor.
• Office and iWork documents: Word, Excel, PowerPoint, Pages, Numbers and Keynote files, as well as RTF and .odt, are shown with the preview built into macOS. Layout and fonts may not match the original app exactly, and they can't be edited.
• Mail messages, contacts, web archives, audio, video and fonts: also shown with the macOS preview. Audio and video don't play automatically.

Which formats can be previewed depends partly on your macOS version and which apps you have installed.

Resomark doesn't open archives, disk images, installers, executables, apps or other packages. Clicking one shows Choose App to Open With…, to hand it to another app.

Right-click any file in the sidebar to choose Open with Default App or Reveal in Finder.

With Resomark installed, select a Markdown or code file in Finder and press Space: the preview looks the same as in Resomark's editor. Math and Mermaid diagrams aren't drawn in this preview.

• What is a Workspace
• Editing with Live Preview