• avono AG
  Of course, we use this plugin in our own wikis
• Apache Software Foundation
  "I'm a huge fan of PlantUML for communicating design.
  It would be very useful to be able to do this directly in the Confluence wiki as opposed to exporting/uploading/attaching exported images. There is a PlantUML Confluence plugin for this."

• Human Factor Labs
  "Useful Plugins" (Slide 10)

• The group SRWT (TEC Belgium www.infotec.be) 
  "Your plugin is really cool !! It’s very usefull to design so quickly UML diagrams in Confluence." 
• www.crosswind.ch
• Swicon in Hungary
• CONTINENTAL DIGITAL SERVICES France
• There are a lot of other people who are using that plugin according to comments, issues and download figures

Are you using the plugin? Please send us a short email.