Airbnb

Sierra

Airbnb

Airbnb is a two-sided marketplace. Hosts list their homes, apartments, treehouses, or whatever else they've got.

Guests book and pay through the platform. Airbnb takes a cut from both sides — roughly 3% from hosts and up to 14% from guests as a service fee.

That's it. They don't own a single property.

They just built the world's largest hotel chain without owning a single bed.

Sierra

Companies pay Sierra to run their customer service with AI agents instead of hiring rooms full of humans. The agent talks to your customers over chat.

It answers questions. It processes returns.

It updates subscriptions. Here is the clever part.

Sierra charges based on outcomes, not seats. Brands pay when the AI actually resolves a problem, not just for having the software installed.

That pricing is unusual. Most software charges a flat monthly fee no matter what.

Sierra only gets paid when the bot does the job.

Airbnb

In 2007, Brian Chesky and Joe Gebbia were two Rhode Island School of Design grads living in San Francisco and struggling to make rent. A big design conference was coming to town and every hotel was booked solid.

They bought three air mattresses, put up a simple website called AirBed & Breakfast, and charged $80 a night including a homemade breakfast. Three strangers actually showed up.

That was it — the entire origin story of a $75 billion company is three air mattresses and desperation.

They recruited Nathan Blecharczyk, a Harvard-trained engineer Joe knew, to build the real website. But nobody wanted to fund them.

They applied to 15 investors and got rejected by every single one. To keep the company alive during the 2008 election, they designed limited-edition cereal boxes — Obama O's and Cap'n McCain's — and hand-assembled 500 of each.

They sold the Obama O's for $40 a box and made $30,000. That cereal money literally kept Airbnb from dying.

Paul Graham at Y Combinator finally let them into the Winter 2009 batch — reportedly because the cereal stunt proved they were "cockroaches" who would never die. YC invested $20,000.

Within a few months, Sequoia Capital led a $600,000 seed round. The rest is history.

Sierra

Bret Taylor had already done the impossible twice. He co-created Google Maps.

He later became co-CEO of Salesforce, chaired Twitter's board during the messy Elon Musk takeover, and became chairman of OpenAI in late 2023. Clay Bavor spent 18 years at Google, most recently running its Labs group.

The two friends left their big jobs in 2023 to build something together. They picked customer service on purpose.

It is the least glamorous corner of software. Their logic was simple.

Companies hate their support costs. Customers hate waiting on hold.

AI that actually resolves problems could fix both sides at once. They launched Sierra in February 2024 with $110 million from Sequoia and Benchmark.

Airbnb

The early growth was pure hustle. Chesky and Gebbia flew to New York — their biggest market — and went door to door visiting hosts.

They noticed the listings with bad photos got no bookings. So they offered free professional photography to every host.

Bookings exploded. That single move — better photos — was probably worth more than any ad campaign they ever ran.

They also pulled one of the most legendary growth hacks in startup history. They reverse-engineered Craigslist's posting system so that Airbnb hosts could cross-post their listings to Craigslist with one click.

Craigslist had millions of people looking for rentals. Airbnb had none.

The hack funneled Craigslist's traffic straight into Airbnb. It was borderline shady and absolutely brilliant.

Word of mouth did the rest. Every guest who had a great stay told their friends.

Every host who made easy money told their neighbors. The product sold itself because both sides benefited immediately.

By 2015, Airbnb had more listings than the top five hotel chains combined.

Sierra

Sierra went straight for big brands, not tiny startups. SoFi, Ramp, ADT, Sonos and Brex signed up early.

By 2026 it said more than 40% of the Fortune 50 were customers. The trick was trust.

Enterprises are terrified of an AI bot going rogue and insulting a customer. So Sierra built guardrails and let each company control exactly how the agent behaves.

Bret Taylor's contacts did the rest. When the chairman of OpenAI calls a Fortune 500 CEO, they pick up.

Sierra hit $100 million in annual recurring revenue in November 2025, seven quarters after launch, and $150 million by February 2026. In April 2026 it launched Ghostwriter, which builds and deploys a new agent from a plain-English description.

Airbnb

Regulation. Full stop.

Cities around the world have gone to war with Airbnb. New York, Barcelona, Amsterdam, Paris, Berlin — all have passed laws restricting or outright banning short-term rentals.

The hotel lobby has spent hundreds of millions fighting Airbnb at every level of government. In New York City, a 2023 law essentially banned most Airbnb listings overnight.

Then COVID hit. In March 2020, Airbnb's business dropped 80% in eight weeks.

Chesky had to lay off 1,900 employees — 25% of the company — in a single memo that became famous for how honest it was. He gave everyone 14 weeks of severance and a year of health insurance.

The company burned through its IPO plans and took on $2 billion in emergency debt at brutal interest rates.

But here's the thing — COVID also saved them. People stopped wanting hotel lobbies and started wanting isolated cabins and rural homes.

Airbnb's bookings came roaring back by summer 2020, and the rural/unique stays trend became permanent. They IPO'd in December 2020 at a valuation that stunned everyone.

Sierra

Everyone is building AI customer service agents right now. Decagon has raised at a multi-billion valuation.

Salesforce, ServiceNow and Intercom all shipped their own agents. Sierra is not the cheap option.

It sells premium AI to giant companies that move slowly. The bigger risk sits underneath the product.

Sierra does not make its own AI models. It rents them from providers like OpenAI and Anthropic.

If those model makers decide to compete directly, Sierra's edge gets thin fast, and its co-founder chairing one of them only makes that question louder. A $15.8 billion valuation on roughly $150 million in revenue leaves almost no room for a stumble.

Airbnb

Airbnb Stays is the core product — book someone's home instead of a hotel. Airbnb Experiences lets you book local activities run by hosts, like cooking classes in Rome or surf lessons in Bali.

Airbnb Luxe is the ultra-premium tier — think private islands, castles, and villas with dedicated concierge service. Airbnb Plus, an inspected-homes tier, was wound down in 2023 after proving too costly to verify at scale.

Categories (launched 2022) lets you browse by vibe — treehouses, lakefront, tiny homes, mansions — instead of just searching by location.

Sierra

The core product is the Sierra AI agent. It is a branded customer service bot that companies deploy on their website, app, and phone lines.

It handles the boring stuff. Order tracking.

Refunds. Password resets.

Account changes. Sierra also built its own tools to test and monitor these agents so they do not make things up.

In 2024 the company added a voice version that talks to customers on the phone. In April 2026 it added Ghostwriter, a tool that builds and deploys a new agent from a plain-English description.

The whole pitch is one AI agent that carries your brand's name and never sleeps.

Airbnb

Y Combinator, Sequoia Capital, Andreessen Horowitz, Greylock Partners, Founders Fund, General Atlantic, Jeff Bezos (personal investment)

Sierra

Sequoia Capital and Benchmark wrote the first checks at launch in February 2024, $110 million between them. Greenoaks Capital then led both the $175 million round in 2024 and the $350 million round in September 2025.

In May 2026 Tiger Global and Google's GV led a $950 million round at a $15.8 billion valuation, with Benchmark, Sequoia and Greenoaks back in. That takes total funding to about $1.6 billion.

That is partly the product and partly Bret Taylor. Investors bet on founders who have already built billion-dollar things.