I'd also mention Nextcloud Forms. A common web development task is to automate something whenever a new form result appears. For example, to publish a review on the website while also sending a notification to the marketing department, recording a conversation in the CRM and sending the client a ticket number. This is often done by polling a CSV or JSON export of the results. Nextcloud offers this functionality, and it's reasonably private when self-hosted. Also due to its lack of end-to-end encryption its forms load much faster and on older devices, too.

I would like to know what exactly these forms are and how to create one.