Do you look for a good quality Nextcloud service with CalDAV? NextFiles is a high quality , hight privacy german based cloud provider, a fast and secure Nextcloud service in a German data center with ISO 27001 certification.
The full functionality of Nextcloud, however, is accessed and managed through its web interface via any modern browser on any platform. If you want to self-host Nextcloud then it can be installed on any Linux computer. It can also be installed in Windows and macOS systems using a Virtual Machine. A popular option is to use a Raspberry Pi as a low-cost Nextcloud server. We do have concerns about whether these machines have the oomph needed for the job, although this may be addressed by the much more capable new Raspberry Pi 4 (especially models with 4GB of RAM).
In addition, these apps are lightweight and incredibly easy to integrate with your NextCloud server in just a few clicks. Being open source, the community will always continue to deliver more features and provide long-term support for the most popular applications to keep your environment running in an ideal state. NextCloud Main Features Summed Up: Open source cloud storage, Sync files from your local machine using the desktop client, Manage contacts, calendars, and scheduled tasks, Ability to manage read/write permissions between all account users, Create public URLs for sharing files, Browser-based text editor, Full library of free and open source apps and plugins to use with your account, Can connect to both Dropbox and Google Drive, Monitoring, Plans to add further video conferencing features in the future, Self-hosted cloud storage.
End-to-end encryption: For ultimate privacy and security, Nextcloud offers end-to-end encryption (e2ee). This means you encrypt your own files locally before uploading them to the cloud. They can then only be decrypted inside apps for which you have the key. E2ee can be enabled on a per-folder basic and synced across. In addition to the actual content, file names and folder structure in e2ee folders are hidden from the server. Nextcloud uses X.509 certificates to verify public keys, an AES-128-GCM (NoPadding) cipher to encrypt private keys, PBKDF2 with HMAC SHA1 authentication for key derivation, and a BIP39 mnemonic as a password. Full details are available in a white paper.
Nextcloud gives you access to all your files wherever you are and whatever device you use. The easy web interface allows you to share files with other users on your server, to create and send password protected public links, to let others upload files to your cloud and to get notifications on your phone and desktop when a user on another cloud server shares files directly with you. And you can do all these things from the desktop or mobile clients, too. The Nextcloud Calendar and Contacts apps allow you to store, sync and share your plans and contacts. You can share with users or groups on your server or sync the calendar or contacts with your devices and access them wherever you are. The Calendar and Contacts app feature: Easy to use interface, Private and shared calendars and addressbooks with permissions management, CalDAV and CardDAV sync with third party clients both on mobile and desktop (i.e with Thunderbird). See additional info on OnlyOffice Nextcloud.