AutoCanary
A warrant canary is a regularly published statement that a company hasn’t received any legal orders that it’s not allowed to talk about, such as a national security letter.
Canaries can help prevent web publishers from misleading visitors and prevent tech companies from misleading users when they share data with the government and are prevented from talking about it. One such situation arose — without a canary in place — in 2013, when the U.S. government sent Lavabit, a provider of encrypted email services apparently used by Snowden, a legal request to access Snowden’s email, thwarting some of the very privacy protections Lavabit had promised users. This request included a gag order, so the company was legally prohibited from talking about it. Rather than becoming “complicit in crimes against the American people,” in his words, Lavabit founder Ladar Levison, chose to shut down the service.