Sarahah

Sarahah () was a Saudi Arabian social networking service for providing constructive feedback. In Arabic, "sarahah" means "frankness" or "honesty". It was created by Zain-Alabdin Tawfiq in the end of 2016 and reached a sudden worldwide success by mid-2017. This growth is considered to be deeply related with the release of a Snapchat update that allowed people to share URLs on their snaps.
Sarahah allowed people to text messages to others and the person reading that could then reply anonymously. Initially, it was meant for workers to compliment their bosses.
It was released on the US Apple App Store on June 13, 2017, and also had users in several other countries including Canada, India, and Lebanon. An update was released by Snapchat on July 5. Within two weeks, it was at the number 1 position. The rise was also seen in a Google Trends report.
On 26 August 2017, it was reported that the Sarahah mobile app quietly uploads the user's address book to its web servers.
Spam was frequent, sent by third-party apps claiming to be able to reveal the usernames of anonymous senders.
On 12 January 2018, it was reported that a woman in Queensland, Australia had started a petition to have the app and others like it banned, after friends of her 13-year-old daughter sent her abusive messages, including ones suggesting that she kill herself. A news report from the Australian Special Broadcasting Service (SBS) stated that the child's mother, Katrina, "called on Apple's App Store and Google Play to stop downloads of Sarahah, which allows people to leave anonymous feedback for each other". On 21 February Katrina posted a message declaring success, saying that both Apple and Google had removed the app from their stores.
Notable uses.
NGOs.
An Indian NGO, Ungender, has used Sarahah to tackle the issue of sexual harassment