Precursor vs FluidUI

A free tier with all mockup functionality is available. Free tier is limited by lacking ability to save mockups privately and additional services provided by Precursor like voice chat and registered subdomains.

Share a link with teammates and they can jump right into your doc. You'll see their changes as they happen, and the built-in voice chat makes design meetings effortless.

The learning curve is relatively low compared to other software that supports animations/transitions. Both building the wireframes and designing the interactions is all drop and drag.

Work with your team on a design. Connect on live video calls and chat or add comments.

You can simulate all the typical iOS gestures such as tap, double tap, swipe & long hold. These gestures then can trigger animated transitions such as sliding, fading, pop in, & flip. This enables you to create very realistic interactable demos of your app. Checkout the demo page for some examples.

Every action you or your team takes automatically creates a revision you can easily revert to.

The UI library is huge and very high quality. All the UI required to design iO7 apps is included as well as iOS 6 and basic wireframing elements. For example in iOS7 it provides:

• Backgrounds
• Navigation & status bars
• Layouts (list pickers, maps, keyboards, scroll etc)
• Controls
• Typography
• Icons

Using the app is feels very snappy.

They have a very reasonable free tier with the paid versions starting at $12/month.

You can preview your designs live in the browser as well as send them to a mobile device to better simulate the UX.

Fluid isn't just about wireframing static screens. You can plan out all the user flows and then define the transitions between them. This is really handy for planning out the entire user workflow.