Best AI Tools for App Prototyping and UI Design
Figma AI remains the default for collaborative product design, with Penpot as the strongest open-source alternative. Visily AI and Galileo AI turn a description or a sketch into editable screens, which is fastest for early exploration, and Marvel AI covers clickable prototypes and hand-off.
Quick comparison
| Tool | Pricing | Free tier | Best for | Details |
|---|---|---|---|---|
| Figma AI | Freemium | Yes — free plan with limited files, version history and AI usage | Browser-based interface design tool where AI assists inside the editor, with multiplayer e | Review → |
| Visily AI | Freemium | Yes — free plan with a limit on screens and collaborators | Wireframing tool for non-designers that turns screenshots and prompts into editable screen | Review → |
| Penpot | Free | Yes — open source and self-hostable at no licence cost | Open-source design and prototyping platform built on web standards, self-hostable and free | Review → |
| Galileo AI （Stitch） | Freemium | Yes — free usage with quotas during preview | Google Stitch generates editable interface designs from a text description or a sketch, as | Review → |
| Marvel AI | Freemium | Yes — free plan with a limit on projects and collaborators | Design and prototyping platform that runs from wireframe to user test in one place, free f | Review → |
How to choose
Prototyping tools differ in how much of the work they remove. Prompt-to-UI tools remove the blank canvas, producing screens you then restructure — useful early, less so once a design system exists. Collaborative platforms remove coordination cost instead, which is the bigger win on a team. Before adopting anything new, check that it can export to a format your developers already use; a prototype that has to be redrawn by hand costs more than the time it saved.
All 5 tools in App Prototyping
Figma AI
Collaborative design canvas with AI features for layouts and prototypes
Freemium
Visily AI
Creates wireframes and hi-fidelity UI from prompts or screenshots
Freemium
Penpot
Open-source design and prototyping tool for product teams
Free
Galileo AI （Stitch）
Freemium AI design assistant for Figma
Freemium
Marvel AI
Wireframing, prototyping and user testing for design validation
Freemium
Questions about App Prototyping
Can AI design a full app interface?
It can generate screens and layouts from a description, which is useful for exploration. Consistent design systems still need a designer's judgement.
Is there an open-source alternative to Figma?
Penpot is the most established open-source option for collaborative interface design.
Where does AI fit in a normal design workflow?
Most commonly at the start, for turning a brief into first-pass screens, and for repetitive production work such as resizing and variants.