There are two established diagramming apps for Confluence Cloud.
It’s hard to know which is the best, so we’ve summarized and compared the functionality on this site.
Data Privacy and Security
The Confluence Cloud architecture for add-ons means that add-ons no longer run on the same machine as Confluence, as is the case for Confluence Server. Gliffy uses traditional server-based architectures that involve passing your user authentication to their server, allowing transit of your data through their servers for save/load operations and actually storing your data on their servers.
One of the key issues with moving to the cloud is trust. Atlassian are investing heavily in security, privacy and compliance for their cloud operations. Establishing that trust level needs a lot of information, transparency and education. Repeating that process for each add-on vendor, in addition to Atlassian, is a time consuming task.
With draw.io, a stateless/serverless architecture is used. This means that your user authentication is only stored in your browser. It also means that when you save/load your diagrams that diagram data goes directly between your browser and Atlassian's servers. It is neither stored, nor transits through third-party servers for persistence operations.
draw.io is open source, you can inspect the code you are running at any time.
draw.io is also complies with Atlassian's Cloud Security Policy. That means we have fully tested processes for backups (easy when you don't store any data) and disaster recovery.
draw.io has status monitoring performed publicly by an independent third-party, Pingdom. Pingdom tests the draw.io site every single minute, 24/7, from multiple locations. Uptime in 2015 and 2016 was 100%, not a single minute of outage. Only draw.io publishes these numbers.
draw.io is priced competitively relative to Gliffy in Confluence Cloud. Gliffy costs almost as much per user as Confluence Cloud, there is no commercial justification for this.
Atlassian only offers the ability to license all users within a Confluence instance. We understand that you only need a sub-set of your users editing diagrams, draw.io pricing reflects this.