Dash vs Zest: What are the differences?
Dash: Gives your Mac instant offline access to 150+ API documentation sets. Dash is an API Documentation Browser and Code Snippet Manager. Dash stores snippets of code and instantly searches offline documentation sets for 150+ APIs. You can even generate your own docsets or request docsets to be included; Zest: FOSS Docs Browser with DevDocs and Stack Overflow. Find what you need without Internet access. Offline search tool for developers. Find what you need without Internet access.
Dash and Zest can be primarily classified as "API Documentation Browser" tools.
Zest is an open source tool with 203 GitHub stars and 10 GitHub forks. Here's a link to Zest's open source repository on GitHub.