plasmic

Plasmic is a visual builder for React apps and sites that plugs into your real codebase. Designers and non-developers drag and drop UI, developers wire in custom React components and data, and nobody's stuck exporting dead mockups. The client libraries are MIT and free; the Studio you actually build in is a hosted app.

Self-hosting is technically on the table, the platform directory is AGPL, but it's a full app plus backend plus database and it's barely documented for self-host. In practice you use the hosted Studio. So read this less as "free self-hosted tool" and more as "SaaS with an open client."

The free tier is real: unlimited projects, a headless CMS, custom domains, three collaborators, with a Plasmic badge on your site. Paid starts at $39/mo to drop the badge, $103/mo for a bigger team and AI, and $399/mo for A/B testing and scheduling. The gates are seats, advanced content features, and branding. Solo builders and tiny teams do fine free. The moment you need a fourth collaborator or want the badge gone, you're paying.

The catch is the one every open-core visual builder has: the free tier is a real product right up until your team grows, and then the seat cap does exactly what it's designed to do. If you want an open alternative to Webflow or Builder.io that lives in your codebase, Plasmic is a strong one. Just go in knowing the hosted Studio is the actual product.