I believe Obsidian are using ProseMirror or CodeMirror, the logo is at the bottom of CodeMirror so I assume it is the latter. There was this forum post from one

I believe Obsidian are using ProseMirror or CodeMirror, the logo is at the bottom of CodeMirror so I assume it is the latter. There was this forum post from one of the Obsidian team a few years back asking about it https://discuss.codemirror.net/t/implementing-wysiwyg-markdown-editor-in-codemirror/2403 https://discuss.codemirror.net/t/implementing-wysiwyg-markdo... https://codemirror.net https://codemirror.net https://prosemirror.net https://prosemirror.net