When comparing OmniGraffle vs Moqups, the Slant community recommends Moqups for most people. In the question“What are the best mockup and wireframing tools for websites?” Moqups is ranked 1st while OmniGraffle is ranked 17th. The most important reason people chose Moqups is:
Moqups is built in HTML5 and standard Javascript, so it doesn't require any plugins to use. The application is very fast to use.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great for web layouts
Pro Fast and doesn't require any plugins
Moqups is built in HTML5 and standard Javascript, so it doesn't require any plugins to use. The application is very fast to use.
Pro Supports 960gs
As well as a standard snap-to-grid, Moqups supports the 960 gridsystem.
Pro Free tier
The Free Plan offers 2 active projects with at most 300 stencils each and 5 MB of storage. This plan does not include: Master Pages, Real Time Collaboration, Privacy Settings, Unlimited Revisions, Unlimited Project Archiving and Teams.
Pro Clean design and very intuitive
Pro Keyboard shortcuts
Moqups has an extensive list of keyboard shortcuts. Simply type some A-Z letters to search for components. F1 for an overlay help screen.
Pro Modern Material elements
Pro Free upgrades for nonprofit/education
Cons
Con Help section could use improvements
Con Mac Only
OmniGraffle is a great tool, but its utility is limited by being trapped on one platform.