WhatsApp

• 1. Introduction

  ›

  WhatsApp reported more than 3 billion monthly active users in May 2025, which makes it the most used messenger app in the world. Its name is a pun, built to sound like the greeting "what's up". Yet the service began as little more than a way to show, inside a phone's contact list, whether a friend was at work or on a call.

  By 2016 it had become the main means of Internet communication across the Americas, the Indian subcontinent and large parts of Europe and Africa. How did a status board turn into that? Why did a small company draw an offer that set a record in the history of venture-backed startups? And why have spyware makers, regulators and whole governments treated an app for sending greetings as something worth hacking, taxing or blocking?

  17517

• 2. From Status to Chat

  ›

  On the 24th of February 2009, Jan Koum incorporated WhatsApp Inc. in California. A month earlier he had bought an iPhone, and he and Brian Acton, both former Yahoo employees, had decided to build something for the App Store.

  Their conversations often took place at the West San Jose home of Alex Fishman, a Russian friend of Koum. To go further they needed an iPhone developer. Fishman searched RentACoder.com, found a Russian developer named Igor Solomennikov, and introduced him to Koum.

  The app reached the Apple App Store in May 2009 and BlackBerry App World the following month. Early versions kept crashing. Koum considered quitting to look for a new job, but Acton urged him to wait a few more months.

  In June 2009 only a handful of Fishman's Russian-speaking friends had downloaded the app. Then Apple launched push technology, which let users be pinged even when the app was closed. Koum updated WhatsApp so a user's whole network was told when a status changed. To his surprise, people used it to trade jokey custom statuses such as "I woke up late" and "I'm on my way." Fishman later said, "At some point it sort of became instant messaging."

  WhatsApp 2.0 reached the iPhone in August 2009 with a purpose-built messaging component, and active users suddenly jumped to 250,000. Acton had been working on another startup idea but decided to join. In October 2009 he persuaded five friends from his Yahoo days to put in $250,000 of seed funding. He officially joined on the 1st of November and became a co-founder with a stake.

  Other phones followed. Koum hired Chris Peiffer, a friend in Los Angeles, to build a BlackBerry version, which arrived about two months later. Symbian came in May 2010 and Android in August 2010. Google made multiple offers for the company in 2010, and every one was declined. To cover the cost of sending verification texts, the service had also switched from free to paid.

  That payment model lasted until January 2016, when Koum announced that the one-dollar annual fee would be dropped and that the app would never show third-party ads.

  2413285655

• 3. Billions of Messages

  ›

  In August 2012 WhatsApp was carrying ten billion messages a day. That was up from two billion in April of the same year and one billion the previous October.

  Money arrived alongside the traffic. In early 2011 the app ranked among the top 20 in the U.S. Apple App Store. In April 2011 Sequoia Capital invested about $8 million for more than 15 percent of the company, after months of negotiation by partner Jim Goetz. By February 2013 the service had about 200 million active users and just 50 staff, and Sequoia added another $50 million at a valuation of $1.5 billion.

  On the 13th of June 2013 the company announced a new daily record of 27 billion messages processed. By December 2013 it had 400 million monthly active users. The books still showed red ink, with $148 million in expenses and a net loss of $138 million. The Financial Times summed up the effect by saying WhatsApp "has done to SMS on mobile phones what Skype did to international calling on landlines."

  On the 22nd of April 2014 the service passed 500 million monthly users, with 700 million photos and 100 million videos shared every day. On the 24th of August 2014 Koum announced on Twitter that the count had passed 600 million. About 25 million people were joining each month, or roughly 833,000 a day. By early January 2015 the total was 700 million, and daily traffic topped 30 billion messages.

  The milestones kept coming. The service reached 900 million users in September 2015 and one billion by February 2016. It passed 1.2 billion in February 2017 and 1.5 billion monthly users by the end of that year. In January 2020 it reached over 5 billion installs on the Google Play Store, only the second non-Google app to do so. February 2020 brought the 2 billion mark.

  In May 2017 users were spending over 340 million minutes a day on video calls, which is roughly 646 years of calling every day.

  India is by far the largest market. WhatsApp crossed 50 million monthly users there in May 2014 and 70 million in October 2014, which made India 10 percent of the whole user base. By February 2017 it had 200 million monthly users in India. In Israel, according to Globes, the app was installed on 92 percent of smartphones by 2013, and 86 percent of users reported daily use. In July 2024 the United States reached 100 million users.

  The field of rivals is crowded. iMessage has an estimated 1.3 billion active users, WeChat 1.26 billion and Telegram 1 billion. Viber has 260 million, LINE 217 million, Signal 70 million and KakaoTalk 57 million. Telegram and Signal both tended to see registration spikes during WhatsApp outages and controversies. In 2016 WhatsApp was even accused of copying features from a then-unreleased version of iMessage.

  2832454651

• 4. The Facebook Purchase

  ›

  On the 19th of February 2014, Facebook agreed to buy WhatsApp for about US$19 billion. It was the largest acquisition the company had made, and the largest ever for a venture-backed firm. Sequoia Capital saw a return of roughly 5,000 percent on its first investment.

  The price had three parts: $4 billion in cash, $12 billion in Facebook shares, and another $3 billion in restricted stock units for founders Koum and Acton. Employee stock was set to vest over four years after closing. Days after the announcement, users suffered a loss of service and took their anger to social media.

  Facebook's decision drew on data from Onavo, its research app for tracking competitors and spotting startups that were doing unusually well. Some users fled. Telegram claimed 8 million new users after the news, and Line claimed 2 million.

  At the Mobile World Congress in Barcelona that month, Mark Zuckerberg tied the deal to his Internet.org vision. TechCrunch described the plan as a bundle of free basic services, "a 911 for the internet". Three days after the announcement, Koum said voice calls were coming, that WhatsApp-branded phones would be sold in Germany, and that the goal was to be on every smartphone.

  The relationship was never smooth. On the 30th of November 2015, the Android client made links to Telegram unclickable and impossible to copy. Multiple sources confirmed it was deliberate, and WhatsApp offered no explanation.

  On the 18th of May 2017, the European Commission fined Facebook €110 million for providing misleading information about the takeover. In 2014, it said, Facebook had falsely claimed it was technically impossible to automatically combine user information from the two services. Yet in the summer of 2016 WhatsApp had begun sharing data such as phone numbers with its parent for targeted ads. Facebook said the errors were not intentional.

  The founders drifted away. In September 2017 Acton left to start a nonprofit, later revealed as the Signal Foundation, which developed the rival Signal app. In April 2018 Koum announced he was leaving too, amid concerns about privacy, advertising and monetization. They were first believed to have given up $1.3 billion in unvested stock options, but it was later reported that Koum kept $450 million of options through a rest and vest program. Chris Daniels was named as his replacement.

  In January 2021 a new privacy policy removed the old option to refuse data sharing with Facebook and its family of companies. Many users deleted the app for Signal and Telegram. The policy did not apply in the EU, where it would break GDPR. WhatsApp pushed the date back to the 15th of May 2021 and said it would not limit functionality for anyone who declined.

  1920264057

• 5. More Than Messaging

  ›

  In August 2013 WhatsApp added voice messages, letting people send short recordings straight into a chat. Voice calls between two accounts followed in early 2015, and by June 2016 the company's blog counted more than 100 million calls placed per day. Video calls arrived on the 14th of November 2016, and group audio and video calls came in September 2018.

  On the 24th of February 2017 the app launched Status, similar to Snapchat and Facebook stories. In May 2023 it let people edit sent messages within a 15-minute window, a feature Telegram and Signal already had. A year later, in April 2024, a Meta AI assistant became widely available inside the app, able to answer questions and generate images.

  Business became its own track in January 2018, when WhatsApp launched a small-company app and an enterprise platform for large customers such as airlines, e-commerce retailers and banks. Cloud API services followed in May 2022. In India, a JioMart integration in August 2022 let shoppers text special numbers to order groceries.

  Money moved through the app too. In July 2017 India's National Payments Corporation approved a partnership with Indian banks for transfers over the Unified Payments Interface. In November 2020 UPI payments were limited to 20 million users, then 100 million in April 2022, and they opened to everyone in August 2022.

  A far bigger financial idea never launched. On the 28th of February 2019, The New York Times reported that Facebook was developing a cryptocurrency for WhatsApp, with more than 50 engineers under former PayPal president David A. Marcus. It was named Libra, and its wallet was called Calibra, later rebranded Novi in May 2020. Meta ended the Novi project on the 1st of September 2022.

  The newest experiment is a subscription. WhatsApp began testing WhatsApp Plus in April 2026, offering cosmetic and organizational perks such as unique chat themes and more pinned chats, and it launched on the 27th of May 2026.

  4797988793

• 6. Encryption and Plumbing

  ›

  In May 2012 WhatsApp first added encryption, after early criticism that it had been sending information as plaintext. A fuller change came on the 18th of November 2014, when Open Whisper Systems announced a partnership to build the protocol from Signal into each WhatsApp client. WhatsApp confirmed it to reporters but published no documentation.

  In April 2015 the German magazine Heise security used ARP spoofing to check the rollout. It found that Android-to-Android messages were protected but iPhone traffic was not, and it worried that ordinary users could not tell the difference. On the 5th of April 2016, WhatsApp and Open Whisper Systems declared encryption finished for "every form of communication" and let users verify each other's keys. Messages used the Signal Protocol and calls used SRTP.

  The Electronic Frontier Foundation gave WhatsApp 6 out of 7 points on its Secure Messaging Scorecard in 2016. It and other researchers still criticized backups that sat outside the encryption. On the 14th of October 2021, WhatsApp rolled out encrypted backups, protected by either a password or a 64-digit key.

  Underneath, the service runs on a customized form of the open XMPP standard. A 2019 document from the DOJ, filed in the lawsuit against NSO Group, named it "FunXMPP". Each account uses the user's phone number as its username, and the app compares the device's address book with its central database to build a contact list.

  The earliest security was thin. Android and Nokia Series 40 versions built a password from a reversed, MD5-hashed IMEI, while iOS used the Wi-Fi MAC address. A 2012 update replaced these with a random password generated on the server.

  Messages travel by store and forward. A message waits on a WhatsApp server until the recipient acknowledges it, and then it is deleted. If it is still undelivered after 30 days, it is deleted anyway.

  59133

• 7. Spyware and Surveillance

  ›

  In May 2019, hackers used a remote-exploit bug in WhatsApp's calling functions to install spyware on victims' phones. Wired noted that the attack worked even if the target never answered the call. The tool was allegedly built by the Israeli firm NSO Group.

  In October 2019 WhatsApp sued NSO Group in a San Francisco court, saying the exploit had targeted at least 100 human-rights defenders, journalists and other members of civil society. They were among a total of 1,400 users in 20 countries. In April 2020 NSO argued the suit threatened its government clients' "national security and foreign policy concerns". Citizen Lab research linked the users to countries including Saudi Arabia, Bahrain, Kazakhstan, Morocco, Mexico and the United Arab Emirates. In July 2020 a US federal judge let the lawsuit proceed.

  In January 2020 a forensic analysis found that Jeff Bezos had received an encrypted WhatsApp message from the official account of Saudi Arabia's Crown Prince Mohammed bin Salman. The message reportedly carried a malicious file that compromised his phone. UN rapporteurs David Kaye and Agnes Callamard later confirmed the hack, tying it to a Saudi hit list of people close to Washington Post journalist Jamal Khashoggi.

  Edward Snowden added his voice in 2019. He argued that the app was designed with very strong encryption, but that Facebook had since been quietly weakening it.

  Law enforcement access drew scrutiny as well. On the 29th of November 2021, Rolling Stone uncovered an FBI document saying WhatsApp answers warrants and subpoenas within minutes, handing over metadata such as contact information and address books. In January 2022 an unsealed surveillance application showed WhatsApp had begun tracking seven users from China and Macau in November 2021, at the request of US DEA investigators.

  The threats continued. In 2025 WhatsApp alerted 90 journalists and other members of civil society that they had been targeted by spyware from the Israeli firm Paragon Solutions. In April 2025 Austrian researchers extracted 3.5 billion users' phone numbers by making a hundred million contact discovery requests an hour. Meta fixed the enumeration problem in October, and the researchers deleted their copy of the numbers.

  2118

• 8. Pressure From Outside

  ›

  In India, a series of incidents between 2017 and 2020 saw lynch mobs murder innocent people after malicious WhatsApp messages falsely accused them of planning to abduct children. WhatsApp urged users to report fraudulent or violent messages and began labeling forwarded messages for Indian users. It had first limited forwarding in 2018 to fight spam, and it later extended those limits in countries including India and Australia.

  Brazil's 2018 presidential election exposed the same weakness. An investigation found WhatsApp being used to spread fake news, along with US$3 million in illegal concealed contributions. In May 2016 a different Brazilian problem had appeared, when users were tricked into installing a fake app called WhatsApp Gold. Since December 2016, more than 1.5 million people had clicked scam messages that triggered paid text messages.

  Governments responded with blocks. In September 2017 security researchers told The New York Times that WhatsApp was completely blocked in China, and in April 2024 Apple removed it from the App Store there. Iran announced a proposal to block it in May 2014, only for President Hassan Rouhani to order the ICT ministry to stop filtering. Iran blocked it again in September 2022 and unblocked it in December 2024.

  Brazil's courts took a harder line. On the 1st of March 2016, Facebook's Latin America vice-president Diego Dzodan was arrested for not cooperating with an investigation, then released the next day. On the 2nd of May 2016, mobile providers were ordered to block WhatsApp for 72 hours, but an appeal lifted the block in under 24 hours.

  Other bans had different motives. Uganda banned it to enforce a daily social media tax of USh.200. The United Arab Emirates restricted its calls from as early as 2013, reportedly to protect national telecom companies. Cuba blocked it during anti-government protests in July 2021, and Zambia did so during its general election in August 2021. In December 2021 the Swiss army told personnel to use the Swiss service Threema instead.

  Russia was the latest. Officials warned of a possible full ban on the 28th of November 2025, and on the 11th of February 2026 the government blocked WhatsApp entirely. It had at least 100 million users in the country. Authorities cited Meta's unwillingness to comply with Russian law on extremist content and state oversight, and said it could resume operations if it complied and entered into dialogue.

  5352747592