Google Drive - Access and sync your files anywhere
Papermind - Papermind Slack App is a collaborative article-editing and document management platform for Slack
Microsoft OneDrive - Secure access, sharing & file storage
Quip: Team Documents for Slack - Create, share and get notified about Quip docs in Slack
Cryptomator - When it comes to saving your files on a cloud server, it is important to ensure the security of those files. Keeping your delicate files out of the wrong hands can save you a lot of time and hassle. Read more about Cryptomator.
Workflowy - A better way to organize your mind.