try puck craft.js or plasmic

Hi there!

I strongly recommend testing Nodify Headless CMS for your e-commerce platform. It fits perfectly with what you're building.

Test it locally via Docker Compose:

git clone https://github.com/AZIRARM/nodify.git
cd nodify
docker compose up -d

Then open http://localhost:8080 (admin / Admin13579++)

Why Nodify is a great fit:

1. True CaaS (Content as a Service)
Nodify is not just a CMS — it's a full CaaS platform. You can programmatically control everything via API, making it perfect for AI-generated layouts. Import, export, migrate data — all through official clients.

2. Complete Studio
Nodify comes with a full visual Studio where you can manage content, create component-based structures, and organize everything. It's developer-friendly but powerful enough for complex setups.

3. Official clients available

• Node.js
• Java
• Python
• PHP

This means your AI can easily interact with Nodify programmatically to generate pages, apply themes, modify layouts via JSON — no hard-coded templates.

4. API-first & headless
Nodify is built API-first. Works perfectly with React, Next.js, or any stack. Your custom cart and order APIs will integrate seamlessly.

5. Multi-tenant ready
Self-hosted, scalable, and you control everything. Perfect for SaaS.

What you can do with Nodify:

• AI generates page structure via JSON
• Programmatically create content nodes
• Apply themes and colors via API
• Component-based content models
• Multilingual support if needed

GitHub repo: https://github.com/AZIRARM/nodify

Give it a test locally with Docker Compose — I think you'll be surprised how well it fits your AI-generated storefront workflow. It's clean, flexible, and truly open-source.

Good luck with your project! 🚀

Honestly, for your setup the answer is pretty much Puck.

Puck is open source, React-native, exports/imports clean JSON, and as of 0.21 has AI page generation baked in. That last part matters a lot for what you're building -your AI generates the JSON, Puck renders it, user can tweak it. That's the whole loop sorted.
For the editor state it's just a JSON blob per tenant - store it in Postgres, load it on request, done. No vendor lock-in, no per-view pricing surprises as you scale.

If you want more low-level control over the editor UI itself, Craft.js is the other solid option. Same idea - full JSON serialization/deserialization - but you build more of the editor chrome yourself. More work, more control.
I'd avoid Builder.io for multi-tenant SaaS. The pricing is based on visual views across your tenants' traffic, which gets painful fast at scale.
For themes/colors/typography - keep that separate from the layout JSON entirely. Design tokens as CSS variables per tenant in your DB, your AI generates both independently.

GrapesJS gets mentioned a lot in this space but it outputs HTML/CSS rather than a component schema, so AI manipulation is messier. Skip it unless you're doing email templates.