Principle for Designers: Quick Animation Prototyping for Mac

Principle is a Mac app for creating animated, interactive prototypes. It’s focused on one thing: making UI animations feel smooth and polished. Design screens, connect them with transitions, and use the timeline to fine-tune every animation. Principle sits between Figma’s simple prototyping and code-based animation, offering visual timeline control without programming.

Key Specs

How Designers Use Principle

Principle excels at making interactions feel good.

For Mobile App Transitions

Design how screens flow into each other. Pull up a menu with a smooth spring animation, transition between tabs with a slide, or fade in a modal with the right timing. Principle’s auto-animate feature infers animations between states, and you fine-tune with the timeline.

For Micro-Interactions

Build button hover states, toggle switches, pull-to-refresh animations, and loading indicators. These small interactions make apps feel polished. Principle’s timeline gives frame-by-frame control over easing, timing, and sequencing.

For Interaction Demos

Create video exports showing how an interaction should work. Share with developers as a reference. A 5-second Principle video communicates animation intent better than words or static specs. Export as MP4 or GIF for easy sharing.

For Quick Prototyping Before Development

Test interaction ideas before committing to code. Build a prototype in an afternoon, share with the team, iterate based on feedback. When the interaction feels right, hand off to development with the Principle file or video as reference.

Principle vs. Alternatives

Choose Principle if: You’re on Mac, want the fastest path to polished animations, and prefer one-time pricing. Great for mobile interaction design.

Choose Figma if: You want design and prototyping together. Figma’s prototyping is less powerful but more convenient.

Choose ProtoPie if: You need conditional logic, variables, sensor access, or Windows support. More powerful, steeper learning curve.

Choose Framer if: You want code-level control and are building interactive websites, not just prototypes.

Getting Started with Principle

Create your first animated prototype in 30 minutes.

Step 1: Create artboards for each state

Open Principle and create artboards for your screens. Import from Sketch (File > Import) or design directly. Each artboard represents a state: home screen, menu open, detail view, etc.

Step 2: Connect artboards with transitions

Draw a link from a button to another artboard. Principle auto-animates layers with matching names. If “Button” exists on both artboards but in different positions, Principle animates the movement. Name layers consistently for automatic animations.

Step 3: Refine with the timeline

Click an interaction to open the timeline. Drag animation bars to adjust timing and duration. Change easing curves (spring, ease-out, linear) in the inspector. Preview with spacebar. Iterate until the animation feels right.

Principle in Your Design Workflow

Principle fits after visual design, before development.

• Before Principle: Design screens in Sketch or Figma
• During prototyping: Principle for animation and transitions
• After Principle: Export video for handoff, or share Principle file with developers on Mac

Common tool pairings:

• Principle + Sketch for native import and seamless workflow
• Principle + Figma via plugin or rebuild (less smooth but possible)
• Principle Mirror + iPhone for real-device interaction testing
• Principle + video export for sharing with non-Mac stakeholders

Common Problems (and How to Fix Them)

“Auto-animate isn’t working between artboards”

Layers must have identical names on both artboards for auto-animate. If “Icon” on artboard 1 doesn’t match “icon” on artboard 2, no animation. Check layer naming. Group layers the same way on both artboards.

“My animations feel choppy or unnatural”

Adjust easing curves. Linear animations feel robotic. Use spring curves for natural movement, ease-out for elements entering, ease-in-out for repositioning. Play with tension and friction values. Watch Apple’s motion design guidelines for reference.

“I can’t import my Figma file”

Principle doesn’t natively import Figma. Options: use a Figma-to-Principle plugin (search Figma Community), export frames as images and rebuild in Principle, or use Sketch as a middle step (Figma export to Sketch, then import to Principle). None are perfect.

“Clients can’t view my prototypes”

Export as MP4 or GIF for universal sharing. For interactive viewing, clients need a Mac with Principle or an iPhone with Principle Mirror (free). There’s no web-based sharing. For broad stakeholder access, video is most reliable.

“Principle feels limited compared to ProtoPie”

Correct. Principle is intentionally simple: no variables, conditions, or sensor access. It focuses on animation, not logic. If you need conditional flows or device sensors, use ProtoPie. Use Principle for animation refinement, not complex interaction logic.