When comparing Zeal vs Dash, the Slant community recommends Zeal for most people. In the question“What are the best offline documentation browsers?” Zeal is ranked 2nd while Dash is ranked 3rd. The most important reason people chose Zeal is:
You can also download additional "Docsets" if you need them, including ActionScript, JavaScript, OS X, Android, Python and tons of others.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Access over 170 APIs offline
You can also download additional "Docsets" if you need them, including ActionScript, JavaScript, OS X, Android, Python and tons of others.
Pro Filter search by API
Pro Visual Studio Code plugin
Visual Studio Code plugin available.
Pro Easy docsets download
Download docsets from CocoaDocs.org, RubyGems.org, Maven.org (Java and Scala), Packagist.org (PHP) and GoDoc.org.
Pro Supports docsets generated using Doxygen
Pro Great fast documentation lookup
Has a handy sublime plugin. Press CTRL-H and it jumps straight to the docs for that object.
Pro Integrates well with a good selection of apps
They provide very useful integration with apps that are very fitting with using Dash's features. Once integrated, you can really get the feel for being a must have part of the app its integrating with.
Pro Great utility app to use for snippets
Snippet apps come in various forms, such as basic snippet (text) containers and added features with text / keyboard utilities to name a couple. This app not only includes this feature, but takes it a bit further than most by adding unique ways to further customize this practice to your own preference.
Pro Easy to create new docsets in case there isn't one that exits already
Gives plenty of guides and information on how to generate a docset.
Cons
Con Javascript Docs broken by default
The Javascript Docs are broken by default, they require you to manually fix it yourself rather than do anything about it.
Con Forced wait time to view docs
If you use the free version you are very often forced to wait 10 seconds to view something you've chosen to look at. If you change apps or lose focus of Dash, it'll start that 10 second timer over again. A real crappy thing to do to your users in order to get them to buy it. Forcing you to waste your time.