SecureDrop is an open-source whistleblower support system, originally written by Aaron Swartz and now run by the Freedom of the Press Foundation. The first instance of this system was named StrongBox and is being run by the New Yorker. To further add to the naming confusion, Aaron Swartz called the system DeadDrop when he wrote the code.

from Schneier’s blog

You can find the website here and if you have something important to submit and do not want to go through Wikileaks, I think this is the best alternative.

The security audit was done by Schneier himself, who is pretty popular in the cryptography community, the work was started by Aaron Swartz who is also extremly popular, especially since his suicide last year.