Yelp

Sierra

Yelp

Local advertising. Yelp is free for consumers and free for businesses to claim their listing.

Revenue comes from selling advertising products to local businesses — sponsored listings that appear at the top of search results, enhanced profiles with photos and call-to-action buttons, and Yelp Ads that target users searching for relevant businesses. Approximately 95% of revenue comes from local advertising, making Yelp essentially an ad platform for small businesses.

The company also earns from Yelp Reservations, Yelp Waitlist, and transaction-based fees on food orders. Revenue is recurring — businesses pay monthly for advertising packages — but churn is high because small businesses often cancel when they don't see immediate ROI.

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.

Yelp

Jeremy Stoppelman got sick after eating at a restaurant and wanted to find a doctor recommendation online. There was nothing useful.

He and Russel Simmons — both former PayPal employees — started Yelp in 2004, originally as an email-based referral system where you'd email friends asking for recommendations. That didn't work.

But they noticed that the reviews people wrote as part of the referral process were the actual valuable content. They pivoted to a review platform where anyone could write reviews of local businesses — restaurants, dentists, plumbers, mechanics, anything.

The social element was key: reviewers had profiles, could be friends, and the best reviewers became "Yelp Elite" with status and perks. By 2008, Yelp had turned reviewing restaurants into a hobby, a social activity, and for some people, an identity.

Google reportedly offered $500 million to acquire Yelp in 2009. Stoppelman turned it down and took the company public in 2012.

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.

Yelp

User-generated content created a flywheel: more reviews attracted more consumers, which attracted more businesses, which attracted more reviewers. Yelp Elite Squad gamified reviewing, turning prolific reviewers into evangelists who hosted events and recruited new users.

SEO dominance — Yelp pages rank highly on Google for local business searches, driving organic traffic that costs nothing to acquire. City-by-city launch strategy with community managers in each market building local reviewer communities.

Advertising sales team calling local businesses directly — a labor-intensive but effective model for monetizing the platform. Mobile app became critical as smartphones made "find a restaurant near me" a constant use case.

Expansion into services (plumbers, contractors, mechanics) beyond restaurants to increase addressable market.

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.

Yelp

Google is the existential threat. Google Maps reviews have overtaken Yelp in volume and are embedded directly in search results, intercepting users before they ever reach Yelp.

Stock performance has been mediocre — shares are roughly flat over the past five years while the broader market doubled. The business model depends on selling advertising to small businesses, which are notoriously difficult and expensive to sell to (high churn, small budgets, skeptical owners).

Yelp has been accused of manipulating reviews to pressure businesses into advertising — allegations the company denies but which have damaged its reputation. Review fraud (fake positive reviews, competitor sabotage reviews) is a constant battle.

And the broader shift to social media for recommendations (Instagram, TikTok, Reddit) is eroding Yelp's relevance with younger users.

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.

Yelp

Business listings and reviews — 265+ million reviews across every local business category. Yelp for Restaurants — reservations, waitlist management, and ordering integrated into business pages.

Yelp Ads — advertising platform letting businesses target users by category, location, and intent. Yelp for Business Owners — dashboard for responding to reviews, tracking page views, and managing business info.

Yelp Elite Squad — gamified community of prolific reviewers who get invited to exclusive events. Yelp Guest Manager — restaurant management tool combining waitlist, reservations, and table management.

Yelp Knowledge Program — data licensing to power local search across third-party platforms.

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.

Yelp

Pre-IPO investors included Bessemer Venture Partners, Max Levchin, and Peter Thiel's Founders Fund. Yelp went public on the NYSE in March 2012.

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.