Here's a list of tools to help you explore using Webflow for building web apps. It's a liste of no-code connectors and a few alternatives in the mix.
Webflow to Shopify
Cloudcanal
https://docs.cloudcanal.io/docs
Memberstack
Postman
https://webflow.com/blog/upvote-system
Webflow to Wordpress
Filtering
Udesly https://cms-filter2.webflow.io/
Jetboost https://www.jetboost.io/
Finsweet https://cmsdocs.webflow.io/
MixItUp https://www.kunkalabs.com/mixitup/
Custom videos
https://www.udesly.com/webflow-resources/webflow-video-player/
Svelte
https://webflow.com/website/Svelte-Webflow-Budget-App
Firebase
https://firebase-auth.webflow.io/
Restflow
Retrieve data from an external API
https://webflow.com/website/Retrieving-data-from-an-external-API-todo-list
Services that glue things together
https://www.integromat.com/en/
Alternatives
Misc
https://twitter.com/ColleenMBrady/status/1302978991226322945
https://twitter.com/aronkor/status/1326899629963751425
https://university.webflow.com/integrations/firebase-authentication
JasonDarkVideo
https://webflow.com/website/Retrieving-data-from-an-external-API-todo-list
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Why Webflow shouldn't be used to build apps
https://medium.com/better-programming/can-i-use-webflow-as-a-tool-to-build-my-web-app-59f41e99dc34