Sierra

AI agents that serve customers for the world’s largest brands.

What it is

Sierra builds AI agents that answer customers by chat and voice for companies such as Deliveroo, SiriusXM, Rivian and SoFi. The agents act inside the company’s systems to resolve issues.

Why it grew

It started with large design partners and tied its price to results. Customers pay for resolved conversations so the value is easy to prove. More than 40% of the Fortune 50 now use it.

Founders: Bret Taylor and Clay Bavor
Founded: 2023 · public launch February 2024
Headquarters: San Francisco
Growth engine: Enterprise design partners and outcome pricing
Pricing: Outcome-based: priced per conversation or per resolution rather than per seat.

Revenue milestones

Nov 2025: $100M company-reported · 21 months after launch (Doolpa)
Early 2026: $150M+ company-reported (Doolpa)

Funding and deals

Sep 2025: $350M, $10B valuation (Startup Fortune)
May 2026: Series E · $950M led by Tiger Global and GV, $15.8B valuation (Doolpa)

Latest news

2026-05-04: $950M Series E at $15.8B as Sierra agents reach over 40% of the Fortune 50 (Doolpa)
2026-04-22: Sierra acquires Fragment, a YC-backed workflow startup (Startup Fortune)
2025-11: Sierra reaches $100M ARR in 21 months (WebProNews)

Last researched 2026-11-02.