Principle is a macOS-only, one-time-purchase tool built around timeline-based animation and multi-screen app flows. ProtoPie is a no-code, freemium tool built…
Best for Principle: macOS-based designers who want deep, custom timeline control over transitions and a one-time license instead of a subscription, working primarily on multi-screen mobile/web/desktop app flows.
Best for ProtoPie: Teams prototyping logic-driven interactions across multiple device types (mobile, web, automotive HMI, TV, smartwatches, gaming) without writing code, especially where sensors, voice, or real data feeds are involved.
At a Glance
Principle
ProtoPie
Primary category
Design
Design
Rating
Not documented
Not documented
Pricing model
One-time Purchase
Freemium with per-editor monthly or annual subscription tiers
Starting price
$129 (one-time, perpetual license)
Free plan available; paid plans start at $25/month (Basic, 1 seat)
Free plan
Not documented
Not documented
Free trial
Yes
Not documented
Platforms
Mac
Not documented
Team collaboration
Not documented
Not documented
AI features
Not documented
Yes
Public API
Not documented
Not documented
Key Differences
Platform availability
Principle: Native macOS app only, with no Windows or Linux editor; finished prototypes can be viewed via web link on Windows, Linux, macOS, Android, and iOS.
ProtoPie: Not restricted to a single OS in the facts available, and explicitly targets automotive HMI, TV, smartwatches, and gaming interfaces in addition to mobile and web.
Teams without a Mac-based design workflow, or those targeting non-standard device categories, are effectively limited to ProtoPie's broader target list.
Pricing model
Principle: One-time $129 purchase with a free trial before buying; no recurring subscription fee.
ProtoPie: Freemium with a free tier to start prototyping, but paid plan pricing is not published on the marketing site.
Principle's cost is fully transparent and paid once; ProtoPie's true cost for paid features can't be evaluated without contacting sales.
Interaction complexity and inputs
Principle: Timeline-based custom animation curves and a multi-screen flow view for connecting app screens.
ProtoPie: No-code logic using variables and formulas, native device sensors, voice interactions, and multi-/cross-device coordination.
ProtoPie supports more complex, data-driven, or sensor-based interactions than Principle's timeline/transition-focused model documented here.
Collaboration and sharing
Principle: No team collaboration or commenting features are mentioned; prototypes are shared via a web link.
ProtoPie: Shareable interaction recordings let teams record and share interactions via links for review.
Teams that need built-in review workflows have a documented option in ProtoPie that isn't described for Principle.
Feature-by-Feature
Core Prototyping
Feature
Principle
ProtoPie
Timeline-based animation
Available
Not documented
No-code logic (variables/formulas)
Not documented
Available
Figma/Sketch import
Available
Available
Multi-screen flow view
Available
Not documented
Native device sensors / voice interactions
Not documented
Available
Platforms & Targets
Feature
Principle
ProtoPie
macOS native editor
Available
Not documented
Cross-platform prototype viewing
Available
Not documented
Automotive/TV/wearable/gaming targets
Unavailable
Available
Pricing & Sharing
Feature
Principle
ProtoPie
Free trial or free tier
Available
Available
Published paid pricing
Available
Unavailable
Shareable interaction recordings
Not documented
Available
Pricing Compared
Starting price reflects the lowest paid tier, not the full cost for every team size or usage level.
Principle
Principle License — $129 One-time (perpetual license, includes 1 year of updates)
ProtoPie
Free — $0 N/A
Basic — $25/month Monthly (1 seat)
Pro — $47/editor/month Monthly or annual (up to 26% savings annually)
Intuitive timeline makes complex animation approachable
Strong Figma and Sketch interoperability
Instant, no-install web sharing for stakeholder feedback
Native macOS performance
Cons
Mac-only, no native Windows or Linux version
Slower update cadence than larger, VC-backed competitors
No built-in design-to-code export
Steep learning curve for complex, code-like interactions
One-time price includes only one year of free updates
ProtoPie
Pros
Enables far more realistic, hardware-aware prototypes than typical design tools
No-code interaction model is accessible to designers without engineering skills
Supports complex multi-screen and connected-device prototyping via Connect Core
Enterprise tier offers private server deployment for security-sensitive teams
Free plan available for individuals to evaluate the tool before purchasing
Cons
Steeper learning curve than simpler click-through prototyping tools
Per-editor pricing on Pro and Enterprise can add up for larger design teams
Advanced features like Connect Core and user testing require paid add-ons
Enterprise plan requires a minimum of three seats, raising the entry cost for small security-focused teams
Use Cases
Choose Principle: macOS-based designers who want deep, custom timeline control over transitions and a one-time license instead of a subscription, working primarily on multi-screen mobile/web/desktop app flows.
Choose ProtoPie: Teams prototyping logic-driven interactions across multiple device types (mobile, web, automotive HMI, TV, smartwatches, gaming) without writing code, especially where sensors, voice, or real data feeds are involved.
Need both: Design teams that prototype standard mobile app flows on Principle but also need to prototype cross-device or sensor-driven experiences (e.g., wearables or in-car interfaces) may keep both tools for different project types.
Principle
Prototyping mobile app micro-interactions — Designers fine-tune transitions and gestures to match the intended feel of a native app.
Creating motion demos for stakeholder review — Teams share interactive, web-based prototypes to get feedback before development begins.
Producing animated portfolio pieces — Designers export polished video or GIF demos of interface concepts for portfolios and case studies.
ProtoPie
Product design teams validating interactions — UX teams at technology companies use ProtoPie to build realistic prototypes for user testing before handing designs to engineering.
IoT and hardware companies prototyping connected experiences — Teams building connected devices use ProtoPie's sensor simulation and Connect Core add-on to prototype multi-device interactions.
Design agencies presenting realistic concepts to clients — Agencies use ProtoPie to create production-like prototypes that communicate interaction details clients and stakeholders can react to.
Frequently Asked Questions
What platforms does Principle run on?
Principle is a native macOS app (Intel and Apple Silicon); shared prototypes can be viewed on the web from Windows, Linux, macOS, Android, and iOS.
Is ProtoPie free?
A free tier is available; paid plans exist but exact pricing isn't published on the marketing page.
How much does Principle cost?
Principle is a one-time $129 purchase, with options to renew or add seats.
What can ProtoPie prototype beyond phone apps?
Per the site, it supports automotive HMI simulations, TV, smartwatches, and gaming interfaces in addition to mobile and web.
Can I import my existing Figma or Sketch files into Principle?
Yes, Principle supports importing designs from both Figma and Sketch with intelligent merging.
Do I need to code to use ProtoPie?
No, it's built for no-code interactive prototyping using logic, variables, and formulas.