2011 April Funding In Series A round, WhatsApp founders agree to take $8 million from Sequoia Capital on top of their $250,000 seed funding, after months of negotiation with Sequoia partner Jim Goetz.[2] 2011 May Competition SnapChat, a competing photo messaging app, is founded.[6] 2012 January 6 Security An unknown hacker publishes a website that makes it possible to change the status of an arbitrary WhatsApp user, as long as the phone number was known.[7][8] 2012 August Security The WhatsApp support staff announce that messages were encrypted in the "latest version" of the WhatsApp software for iOS and Android (but not BlackBerry, Windows Phone, and Symbian), without specifying the cryptographic method.[9] 2013 February Userbase WhatsApp's user base swells to about 200 million active users and its staff to 50.[2] 2013 July Funding Sequoia invests another $50 million in Series B round, valuing WhatsApp at $1.5 billion.[10] 2013 July 16 Product WhatsApp goes free, with an annual subscription fee of $1 after the first year.[11][12] 2013 August Competition Telegram, a cloud-based instant messaging service, launches.[13] 2013 August Product WhatsApp introduces voice messaging.[14] 2014 February 19 Company Facebook, Inc. announces its acquisition of WhatsApp for US$19 billion, its largest acquisition to date.[15] Facebook pays $4 billion in cash, $12 billion in Facebook shares, and an additional $3 billion in restricted stock units granted to WhatsApp's founders.[16] 2014 March Security Someone discovers a vulnerability in WhatsApp encryption on the Android application that allows another app to access and read all of a user’s chat conversations within it.[17] 2014 November Product WhatsApp introduces a feature named Read Receipts, which alerts senders when their messages are read by recipients. Within a week, WhatsApp introduces an update allowing users to disable this feature so that message recipients do not send acknowledgements.[18] 2015 January 21 Product WhatsApp launches WhatsApp Web, a web client which can be used through a web browser by syncing with the mobile device's connection.[19] 2015 January 21 Product WhatsApp announces its policy on cracking down on 3rd-party clients, including WhatsApp+.[20] Users would not be able to use WhatsApp’s services at all until the third-party apps are uninstalled.[21] 2015 March Product Added voice calls between two accounts.[22] 2015 December Legal WhatsApp is briefly shut down in Brazil after it refuses to place wiretaps on certain WhatsApp accounts.[23] It is shut down in Brazil again on May 2016 and in July 2016.[24] 2016 January 18 Product Jan Koum announces that WhatsApp will no longer charge its users a $1 annual subscription fee.[25][26] There is still no clear plan for monetizing WhatsApp.[27] 2016 March Legal Diego Dzodan, a Facebook executive, is arrested by Brazilian federal police after Facebook fails to turn over information from his WhatsApp messaging account into a judge's request for a drug trafficking investigation.[28] 2016 March 2 Product WhatsApp introduces its document-sharing feature, initially allowing users to share PDF files with their contacts.[29] 2016 April 5 Product, Security WhatsApp and Open Whisper Systems announce that they finish adding end-to-end encryption to "every form of communication" on WhatsApp, and that users could now verify each other's keys.[30][31][32] 2016 May 10 Product WhatsApp is introduced for both Windows and Mac operating systems.[33] 2016 November Product Added video calls between two accounts.[34] 2017 September 5 Product WhatsApp started external testing of an enterprise platform which enables companies to provide customer service to users at scale.[35] Airline KLM launches such a service.[36] 2018 July Product Added group voice and video calls for up to four accounts.[37] 2020 April Product Group calls now allow up to 8 accounts.[38]