Tellonym

Tellonym (neologism, from English "to tell" and German "anonymous") is a free, ad-supported, cross-platform messaging app to have questions answered. Tellonym is an easy way to get feedback and supports the anonymity of the person giving the feedback as well as the possibility to give unsolicited feedback. Currently, a total of 40 million users worldwide are logged on to the portal. As of March 2019, approximately one-third (13 million) of these are German-speaking users. The remainder are mainly from the United States, Great Britain, Brazil and Australia.
The app is developed by Callosum Software. The company's headquarters are in Berlin, Germany
History.
Comparable projects were started with ask.fm in 2010, while the competitor Sarahah from Saudi Arabia also started in 2016. The Tellonym project started in April 2016. 700,000 users registered in May 2017. By June 2018, 2 million users had registered. , the Google App Store indicates more than 10 million registrations. According to the surveys of the Youth Internet Monitor 2018 in Austria, 12 percent of 11 to 17-year-olds use the App.
Technology.
The messages on Tellonym are called "Tells". A user's profile consists of a username and optionally a short description and an emoji, which are obtained during events or can be purchased. The profile is used to collect feedback, about oneself, about work, about any questions. Tellonym can thus be used as a kind of survey tool In addition to friends, complete strangers can access the personal profile via a public link and leave comments there. This makes it easier to leave hurtful or annoying comments. In order to rate other users, it is not necessary to have your own profile, where you would have to provide your name or e-mail address. The provider reserves the right to keep the messages and IP addresses of the end devices for a possibly necessary transmission to criminal authorities. The app allows you to set up a user-based word filter with a maximum of ten words, which prevents "tells" containing the listed words from reaching the user. This word filter is ineffective in practice, as it can be circumvented by exchanging single letters. A timer function can be used to schedule the time of sending the message. 
Cyber-bullying threats.
The possibility to formulate tells anonymously makes it easier for users to insult or harass others, which can lead to cyber-bullying. Since 70 percent of Tellonym users are adolescent girls, they are particularly likely to be unsettled by anonymous insults. In many cases, "drastic insults or even incitements to suicide" can be observed on Tellonym. Digital mechanisms for the prevention of suicide or running amok have not yet been integrated (as of December 2019).