For Sierra, from 🤫 hussh
The work we admire.
Before we ask to build with anyone, we learn their work. Here is Sierra as Sierra describes itself: what it ships, how it prices, the research it publishes, and how fast it has grown.
Who they are
Better, more human customer experiences.
“Sierra helps businesses build better, more human customer experiences with AI.”
- Founded
- 2023, and out of stealth on February 13, 2024Fortune
- Co-founders
- Bret Taylor (CEO) and Clay Bavorsierra.ai/about
- Headquarters
- San Francisco, with offices across the US, Europe and Asiasierra.ai/about
- What they build
- Agent OS, an enterprise platform to build, optimize, personalize and scale customer-facing AI agentssierra.ai
- Pricing
- Outcome-based: customers pay for resolved outcomes, not seatsOutcome-based pricing
- Funding
- About $1.58B raised, including a $950M round at a $15.8B valuation in May 2026 (Tiger Global, GV), as reportedTechCrunch
The product
Agent OS: build, optimize, scale.
Sierra's agents meet customers on chat, SMS, WhatsApp, email, voice, ChatGPT. Every one of those is a place a 🤫 Agent One could meet them on the customer's behalf.
Agent OS
The platform to build, optimize, personalize and scale branded AI agents for customer experience.
Ghostwriter
The agent that builds agents. It turns SOPs, transcripts and plain-English goals into a production-ready, multilingual, multichannel agent.
Agent Studio
The dashboard to build, visualize, configure and manage agents.
Insights
Explorer for deep research over conversations, plus Monitors, Experiments for A/B testing, and Observability.
Agent Data Platform
Personalization: agent memory, customer-data integration, recommendations and proactive next-best-action.
The science
The τ-bench family: rigor for agents.
τ-bench
A benchmark for tool-agent-user interaction in real domains. Can an agent follow policy while working with a simulated user and real APIs? (June 2024)
τ²-bench
Collaborative, dual-control tasks where the agent and the user must coordinate. (June 2025)
τ³-bench: Voice
The same framework, extended to full-duplex voice agents. (March 2026)
The trajectory
How fast Sierra has grown.
Rounds as reported by the press cited below.
The enterprise side, beautifully built
Sierra built the enterprise side of the conversation. We would love to build the customer's side with you.