We also want to increase the trust to our service and the following idea comes to mind. What if we publish our backend source code? Of course, nobody can check that this code is installed on server, however anybody could read it and make sure it makes sense. What do you guys think about that? Would you be interested in seeing BitWhisk source code?
I don't think if there is any mixing service which shares their source code. This would definitely distinguish you from the others. However, wouldn't it expose your method of mixing coins and make it easier for someone to track people who have used your service? What else are you working on right now? Thank you for a non javascript version of your website.