Principle API
No API of any kind. Principle is a Mac-only prototyping app whose whole integration surface is file import from Figma and Sketch and export to HTML, video, GIF, or a Mac app. A long-requested JavaScript API for HTML exports has never shipped.
Frequently asked questions
Principle scores F on the API Report Card. No API of any kind. Principle is a Mac-only prototyping app whose whole integration surface is file import from Figma and Sketch and export to HTML, video, GIF, or a Mac app. A long-requested JavaScript API for HTML exports has never shipped.
Without a usable official API, teams fall back on manual exports, file drops, or one-off vendor integrations. The other option is an unofficial API layer like Supergood that automates the authenticated web app directly.
Principle is a native macOS desktop application for designing animated and interactive user-interface prototypes.
Vertical: misc / horizontal creative tooling (not a Supergood vertical SaaS, not Legal, Healthcare, Real Estate, Compliance, Financial Services, Behavioral Health, Property Management, Fleet, Insurance, etc.). Timeline-based keyframe animation for UI elements (transform, opacity, color, blur, etc.) across multiple artboards.
Low and declining. Principle had a peak moment in 2016–2019 as the go-to Mac tool for high-fidelity UI motion prototypes, especially among iOS designers.
Principle stores and processes only local design IP on a designer's Mac. Specifically: `.prd` Principle document files containing layered artboards, components, animation timelines, drivers/events, and embedded raster/vector assets.
Principle is ~11 years old (initial release 2015, currently in the 6.4x version series). Architecturally it is a native macOS Cocoa/AppKit application built around a custom animation timeline and event/driver runtime.
No public REST/GraphQL API, no SDKs, no webhooks, no OAuth, there is no developer platform at all. Multi-year unanswered community request for a JavaScript API on the HTML export so prototypes could be embedded and externally driven. Full sourced list under Sources below.
Common alternatives include Figma (with native prototyping + Smart Animate), ProtoPie, Framer, Sketch (with native prototyping), Origami Studio (Meta), Rive. Graded alternatives appear under "More from the report card" below.
Grades measure one thing: can a customer's engineering team get their own data out programmatically? We check six things (whether a real API exists, how access is gated, data coverage, auth quality, docs and developer experience, and stability) and roll them into a letter grade. Grades get re-verified, and they only move on evidence.