When comparing iA Writer vs Caret, the Slant community recommends iA Writer for most people. In the question“What is the best Markdown editor for OS X?” iA Writer is ranked 11th while Caret is ranked 20th.
Ranked in these QuestionsQuestion Ranking
Pro Can tell how long it would take to read through what you've written
Pro A mode that brings focus to the sentence you're working on
Enabling Focus Mode will dim the whole text except the sentence you are currently writing on.
Pro Create whole document by including separate images/markdown docs
This is new and very awesome feature in iA Writer 4.0
Pro Markdown support
Pro Noise Free Writing Experience removes even the program bar
The Noise Free Writing Experience is one of the first approaches to create a first class distraction-free environment. The feature hides the Mac program bar when you start writing.
Pro Available for all Apple devices
iA Writer is available for Mac, iPhone and iPad.
Pro Can export a Word document
Pro Syncs using iCloud and Dropbox
iA Writer can sync documents using iCloud or Dropbox from within the editor for use across multiple devices.
Pro Has a heading navigator
Hit ⌘ G to see document titles in a hierarchical view, type and use the arrows to navigate.
Pro Has a file manager
Hit ⌘ T to browse current folder, navigate the file system and manage your files and folders, type to search, right click to create / move / rename / delete items.
Pro Supports multiple cursors / selections
Make ten changes at the same time, not one change ten times - lets you edit multiple lines at once, perform quick and selective find and replace, etc.
Pro Supports context commands
Hit "Enter" to fix spelling, convert list to ordered/unordered/task, convert reference link to inline, jump to reference link definition, jump to footnote definition, visit links, etc.
Pro Supports auto-completions
Auto-completion for paths of links and images, keywords in fenced code blocks, emoji, etc.
Pro Offers inline preview for LaTeX math expressions
Renders LaTeX math expressions as soon as you have finished writing them.
Pro Supports "select more" / "select less" commands
Hit ⌥ ↑ to extend the current selection to the next biggest element and ⌥ ↓ to shrink the selection.
Con No Windows or Linux support
Con Not free
No longer free, try and buy