How Paul English built KAYAK into a $1.8B travel search engine

Executive overview

Travel booking sites in 2004 were cluttered, slow, and showed only their own inventory. Paul English and Steve Hafner built KAYAK as a pure search engine — no transactions, no customer support, just fast and clean results scraped from everywhere.

The insight was that a thin, beautifully designed UI layer on top of existing travel technology could beat incumbents with ten times the resources. Eight years after launch, Priceline acquired KAYAK for $1.8 billion.

The real competitive advantage was simplicity: becoming fast and clean is harder than it looks, and users remember it.

Early career and the serial entrepreneur pattern

• English taught himself to code on a Commodore VIC-20 and sold his first video game, Cupid, at age 16 for $5,000 upfront (before the buyer went bankrupt)
• At Interleaf, he was pushed from engineering into marketing, giving him an early cross-functional view of how software companies sell
• He founded Boston Light Software in 1998 — an early e-commerce/online payments platform — and sold it to Intuit for $33.5 million roughly a year later
• His three core engineers — Bill O'Donnell, Paul Schwenk, Jeff Rago — followed him across multiple companies over decades; recruiting the same trusted team was a deliberate strategy
• English was diagnosed with bipolar disorder at 25; he cycled through medication for 15 years before finding a regimen that worked, and credits meditation and therapy alongside medication

The founding of KAYAK

• English met Steve Hafner by chance at General Catalyst's offices in Cambridge in late 2003; Hafner was a co-founder of Orbitz looking for a CTO
• Over gin and tonics at Legal Seafoods, English agreed to join as 50-50 co-founder — Hafner immediately tore up a term sheet offering a different investor, claiming he was now worth more with a co-founder
• The concept: a search-only travel engine that scraped every airline and hotel site, with no ability to book directly — "search with us, book with them"
• General Catalyst put in $5M; each founder put in $1M; core engineers took large pay cuts (100K vs 400K) in exchange for equity stakes of 1-2%
• The tech team was based outside Boston; Hafner ran the commercial side from Connecticut — a distributed structure unusual for 2004

Building the product

• First beta launched on Cinco de Mayo 2004; public launch in October 2004
• Early KAYAK scraped competitor sites without permission — ask forgiveness, not permission — and had no revenue for the first year or two
• The backend search engine was ITA Software (later Google Flights); KAYAK was deliberately just a UI layer on top
• Expedia's interface was the benchmark to beat: English spent 10 minutes on it the day he agreed to join and concluded it was "epileptic seizure inducing"
• Key design values: speed, cleanliness, simplicity — what users actually remembered about KAYAK, not the breadth of content

Growth and the business model

• Early economics: $1 cost per acquired user, 20 cents revenue per user — losing 80 cents per transaction at scale
• The bet: if the product was good enough, users would return directly (typing kayak.com) without going through Google, making unit economics work
• Reached 70% self-directed traffic, at which point the model became profitable
• Used Orbitz as a "stalking horse" — gave them exclusivity as the booking partner to get signed, then used that proof to recruit airlines to pay KAYAK directly
• By the time of the 2012 IPO, KAYAK had only 200 employees and $300M in revenue — $1.5M per employee
• Raised $200M from Sequoia in December 2007 as a growth milestone; went public on NASDAQ in July 2012
• Priceline acquired KAYAK for $1.8 billion by end of 2012; over half of the 200 employees became millionaires

Leadership style and mental health at KAYAK

• English operated in hypomanic states, waking at 3-4am to sketch product ideas and email the design and engineering leads
• His team developed an informal filter: only act on an idea if English asks for it twice — protecting execution focus from the idea flood
• He describes his management philosophy as building around recruiting: companies thrive only when built around exceptional people
• Gave up equity to engineers at Boston Light when the sale came sooner than expected, forgoing $10M of personal proceeds so the team would benefit more
• After the acquisition, found the public attention and wealth uncomfortable; immediately began giving money away and eventually founded three nonprofits

After KAYAK

• English spent roughly a year transitioning KAYAK under Priceline before leaving; the CEO was unhappy with his departure
• Founded Get Human in 2006 (while still at KAYAK) — a database of customer service shortcuts; still running profitably as a small company funded by advertising
• Taught at MIT, RISD, and Harvard Business School after leaving KAYAK
• Founded Lola in 2015, the day after his non-compete expired — a corporate travel concierge app; later acquired by Capital One
• Relaunched Lola in 2024 as a dating app matching people based on real-time availability to meet in person
• Structures his time with a color-coded calendar: purple (Lola), yellow (nonprofit), green (self-improvement), blue (friends and family)