See also: nocode.tools
Bubble
Bildr
https://www.softr.io - People are saying this is the best no-code tool, even better than Bubble! Unfortunately, it only works with Airtable. But that might be OK. Airtable is very powerful!
Even though this is more for websites than apps, it may be worth trying. It is powerful and easy. Show repeating content from a database (blog entries, job listings, portfolio works). Manage user accounts. Create a community or membership site like Reddit where members can upvote or downvote content. Collect payments. Send form data to many integrations and web hooks.
Webflow
Memberships / Payments