On 24 February 2009, on his birthday at age 33, Jan Borysovych Koum registered WhatsApp Inc. in California. The app did not exist yet. The name was a pun on “what's up.” Five years later he signed the sale to Facebook — around US$ 19,3 billion — in the white Mountain View building where he collected food stamps as a teenager. In May 2025 WhatsApp passed 3 billion monthly users; Koum had already left in 2018 over privacy. The cover shows that parking lot: the welfare office, the tracks, the green bubble.
Fastiv, food stamps, Yahoo
Yan Kum was born in Kyiv, Ukrainian SSR, on 24 February 1976, an only child in a Jewish family. He grew up in Fastiv, about 70 km from the capital. His father managed construction; his mother was a homemaker. Tapped phones, queues, the state in the middle of conversations — he later cited that as his motivation: no ads, no data to sell, a message and a number.
In 1992, at 16, he moved with his mother and grandmother to Mountain View, California. His father stayed in Ukraine and died in 1997; his mother, around 2000. Food stamps, a line at 101 Moffett Boulevard. Poor English. Grocery work, cleaning. Used networking books. He enrolled in computer science at San Jose State and dropped out. Ernst & Young, security testing.
In 1997 Yahoo hired the Ukrainian as an infrastructure engineer. There he met Brian Acton, who interviewed him for the systems security team. Nine years together. On 31 October 2007 — Halloween — both resigned on the same day. Acton tried Facebook and Twitter; both rejected him. Koum visited family in Russia and returned with an idea in his pocket and a newly purchased iPhone 3G.
2009: status, then conversation
Hours of conversation on his friend Alex Fishman's couch. The first WhatsApp was a status in the contacts list: “at the gym,” “busy,” via push. It almost died: iOS 3.0, in June 2009, let any app receive notifications. Koum saw the status turn into conversation. The app crashed; he nearly quit. Acton, unemployed, told him to keep going. In October Acton brought US$ 250 thousand from five former Yahoo employees and earned the cofounder title. On Koum's desk, a sticky note from Acton: “No Ads! No Games! No Gimmicks!”
One dollar per year after the first free year. No advertising. No games. BlackBerry, Android, Nokia S40, Symbian, Windows Phone — the phone people already had, not the one the Valley wanted to sell. Sequoia invested around US$ 8 million in 2011 and another US$ 50 million in 2013 (valuation of US$ 1,5 billion). The only VC, around US$ 58 million in total. In December 2013 the app was gaining a million users a day. 450 million in early 2014. More than Twitter. Revenue around US$ 20 million. Zero advertising spend.
Erlang, FreeBSD, two million sockets
What the Valley bought was not just the bubble. It was one of the internet's leanest systems. At the sale, around 50 engineers and 450 million users — on the order of 10 million users per engineer. Twitter and Facebook, at the same time, counted their teams in thousands. The technical choice: Erlang on BEAM, FreeBSD as the kernel, a fork of ejabberd (XMPP) becoming less and less XMPP, Mnesia in memory, MySQL on disk. One Erlang process per connection, a few hundred bytes, not an OS thread.
Rick Reed — ex-Yahoo, C and performance, new to Erlang — discussed this at Erlang Factory in San Francisco on 30 March 2012. Target: 1 million simultaneous TCP connections per machine. A month later, 2 million. In February, accidentally, 2,8 million (571 thousand packets/s) on a Dual Westmere hexacore box, 24 logical CPUs, 100 GB of RAM, SSD, FreeBSD 8.x. The typical loader:
# /boot/loader.conf.local — WhatsApp, ~2012
kern.ipc.maxsockets=2400000
kern.maxfiles=3000000
kern.maxfilesperproc=2700000
kqueue instead of epoll. kern.ipc.somaxconn far from the default 128, so the backlog would not drop SYNs when an earthquake or a World Cup final reconnected the planet. BEAM above 85% CPU on the 24 logical CPUs. Hundreds of nodes, more than 8 thousand cores, more than 70 million Erlang messages per second, 50 billion user messages per day. LinuxPro is a Linux home; the honest message is that, for that long-lived socket workload, the team preferred FreeBSD. The UNIX that BSD inherited still paid the bills.
February 2014: dinner at Zuckerberg's house
On 9 February Zuckerberg invited Koum to dinner and offered a board seat. Ten days later Facebook announced the purchase. The check: US$ 4 billion in cash, US$ 12 billion in stock (around 8,5% of Facebook), US$ 3 billion in RSUs. Total ~US$ 19,3 billion — the decade's biggest internet acquisition; with RSU vesting, the press sometimes cites US$ 22 billion. Koum ~45% of WhatsApp; Acton just over 20%. Sequoia, around 60 times its investment. Around 55 employees in the building.
They signed at the welfare office. Koum, Acton, Jim Goetz from Sequoia. Zuckerberg promised zero pressure to monetize: “I want you to connect 4 or 5 billion people.” Ads, no. Data cross-linked with Facebook, no. European regulators heard the same thing — Acton later told Forbes he was coached to repeat it in Brussels.
Encryption, the message, and the rift
In 2016 WhatsApp enabled end-to-end encryption at scale, using the Signal protocol (Moxie Marlinspike / Open Whisper Systems). Groups, voice, then video. The sticky note's message did not survive the buyer. Facebook wanted phone numbers, new terms, a bridge to the social graph. Cambridge Analytica worsened the atmosphere. Acton left in September 2017, leaving around US$ 850 million in unvested stock on the table, and tweeted #DeleteFacebook in March 2018. In February 2018 he put US$ 50 million (a loan) into the Signal Foundation and became executive chairman — and later interim CEO of Signal Messenger.
Koum announced his departure on 30 April 2018: air-cooled Porsches, frisbee, “cheering from the outside.” The press and the Washington Post pointed to the same reason: ads, user data, and pressure to weaken encryption in WhatsApp Business. He stayed in “rest and vest” for a few months (~US$ 450 million remaining). He left Facebook's board. Zuckerberg commented on the post, praising what Koum had taught him about encryption. From then on, the app was no longer the sticky note.
The app without its founders
Will Cathcart took over WhatsApp in 2019 and took the chart to 3 billion monthly users (May 2025). In 2025 Meta began showing ads in the Updates tab. On 22 June 2026 Cathcart handed the role to Kunal Shah, founder of CRED (an Indian fintech). In the same package, Meta invested US$ 900 million in CRED (~20%). Chris Cox's internal message: “intuitive grasp of the product's global potential.” India was already the biggest market — around 860 million accounts, according to 2026 figures.
In June 2026 the app opened username reservations for its more than 3 billion users, without abandoning phone numbers. Somalia and India complained about tracking and fraud. Business, channels, a paid Cloud API, a payments superapp on the horizon. The opposite of the sticky note. End-to-end encryption for personal chats is still there; the rest of the house belongs to Meta.
2026: Newlands, silence, the bubble
Koum barely speaks publicly. He collects air-cooled Porsches. Newlands Management Operations, his family office, held at least US$ 15,5 billion in assets on 31 March 2026 (May filing). Forbes and Bloomberg, in 2026, still place him around US$ 15–17 billion. A family foundation around US$ 3 billion. Property in Los Angeles and on the French Riviera. He did not return to the app. Acton remains at Signal, without ads, VC, or an IPO.
The other Ukrainian on this blog is in The history of GitLab — Dmitriy Zaporozhets, another Fastiv-to-Valley story, another angle. The kernel underneath the phone, in Linux turns 35. The classic mail WhatsApp replaced in your pocket, in The history of Postfix.
Timeline
- 24 February 1976 — born in Kyiv, then in the Ukrainian SSR; grows up in Fastiv.
- 1992 — at 16, emigrates with his mother and grandmother to Mountain View, California.
- 1997 — joins Yahoo as an infrastructure engineer and meets Brian Acton.
- 31 October 2007 — both resign on the same day.
- 24 February 2009 — on his birthday, registers WhatsApp Inc.; the app does not yet exist.
- June 2009 — iOS 3.0 enables notifications for any app and status becomes conversation.
- October 2009 — Acton raises US$ 250 thousand from five former Yahoo employees and becomes cofounder; the sticky note is born “No Ads! No Games! No Gimmicks!”.
- 2011 and 2013 — Sequoia invests, first around US$ 8 million and then US$ 50 million; it is the only venture investor.
- December 2013 — the app gains a million users per day.
- February 2014 — Facebook buys WhatsApp for around US$ 19,3 billion; they sign in the welfare office where he collected food stamps.
- 2016 — end-to-end encryption at scale, with the Signal protocol.
- September 2017 — Acton leaves, walking away from around US$ 850 million in unvested stock.
- February 2018 — Acton lends US$ 50 million to the Signal Foundation.
- March 2018 — Acton posts
#DeleteFacebookduring the Cambridge Analytica scandal. - 30 April 2018 — Koum announces his departure over privacy and pressure on encryption.
- 2019 — Will Cathcart takes over WhatsApp.
- May 2025 — the app passes 3 billion monthly users; Meta starts showing ads in the Updates tab.
- 22 June 2026 — Kunal Shah, founder of CRED, takes over; Meta invests US$ 900 million in the Indian fintech.
- 2026 — the app opens username reservations; Newlands, Koum's family office, reports at least US$ 15,5 billion in assets.
Wrap-up
A boy from Fastiv, a food stamp in Mountain View, an iPhone status, Erlang on FreeBSD, and the biggest internet sale of the time. WhatsApp connected the planet with a team that fit on one floor. Its creator left when the message stopped holding true. 3 billion people, Meta in control, Koum in the cover's parking lot — the same kind of building where the line began.
Acton was the other founder. Without the US$ 250 thousand, the sticky note, and the refusal to vest the US$ 850 million, the green bubble might have been just another app with a banner. The story belongs to both. The name on the cover is the boy who chose “what's up” on his birthday.
Cover illustration drawn from a photograph of Jan Koum available on Wikimedia Commons, under the CC BY 2.0 license.
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