Box Shadow app rejected again with no feedback — build showing postMessage and IFRAME keywords

Developers Marketplace Submission
1

Hi folks, :waving_hand:

We recently had our Box Shadow app rejected from the Webflow Marketplace, but this time no specific feedback was provided.

All previously reported issues have already been fixed — Datadog analytics removed, Tailwind compiled locally (no CDN), and no child iframes or postMessage handlers in our code.

However, we’re still seeing a few console warnings inside the Designer:

Datadog Browser SDK: Customer data exceeds the recommended 3KiB threshold
POST https://smart-shadows.design.webflow.com/api/v1/marketplace/resource/search/apps 404 (Not Found)
<link rel=preload> uses an unsupported 'as' value

These appear to originate from webflow-designer.*.chunk.js, not from our app bundle.

We also noticed that even though our source code does not contain any of these keywords:

postMessage  
IFRAME_READY  
INSERT_SVG  
UPLOAD_AND_INSERT_IMAGE

they show up in the final production build after running npm run build.

We’ve searched our entire codebase and node modules and couldn’t find them before build — it seems they might be injected during bundling by a dependency or build tool.

We’re trying to confirm whether these build-time injected strings or Designer-side warnings could have caused our app’s rejection, or if there’s another issue we should address before resubmitting.

Any help or clarification from the Webflow team or community would be greatly appreciated. :folded_hands:

— Shivam
Fluttertop Studio (Box Shadow App Team)

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1 Like
2

Hey @Shivamgoud.23 - first, really appreciate all the time you’ve invested in building the app and adjusting for our marketplace review team’s guidance.

Agree that some points may be related to issues in the Designer. We can work with our teams on ensuring console errors are isolated to just any that come from your app.

In the meantime, I do see new updates to the app were submitted since this post was made and some of the issues raised have been resolved so hopefully you are unblocked! If not, I recommend replying to the review email thread to get more clarity on any of the points they raised.

3

Hey @zachplata,

Thanks so much for checking and for getting back to me! Really appreciate your guidance throughout this process.

Just wanted to share that my app has now been approved — thanks again to the Webflow team for the support. :raising_hands:

— Shivam

1 Like
4

Hi Webflow team

I’ve built a Hybrid App using the Webflow Designer API, and the app is currently working correctly.

I have a few questions about submitting it to the Webflow Marketplace:

  1. For Designer Apps, we usually submit a bundle.zip.
    For Hybrid Apps, what is the correct way to submit the app for review?

  2. My Hybrid App is currently running on ngrok for development.
    Do I need to deploy the app to a production URL (Vercel / Render / Railway, etc.) before submission?

  3. In the Marketplace submission:

    • What should be the Install URL for a Hybrid App?

    • Should it point directly to the Webflow OAuth URL or to my hosted app URL?

  4. Is it required that the app works without ngrok at the time of review?

Any guidance or official docs around submitting Hybrid Apps to the Marketplace would be really helpful.

Thanks in advance