# Sierra

> Sierra is a San Francisco AI company building conversational agents that handle customer interactions for enterprises. Founded by Bret Taylor and Clay Bavor in 2023, it serves more than 40% of the Fortune 50 and was last valued at $15.8 billion after a $950M Series E in May 2026.

- **Founded:** 2023
- **Headquarters:** San Francisco, United States
- **Founders:** Bret Taylor (Co-Founder & CEO), Clay Bavor (Co-Founder)
- **Team size:** ~350
- **Products:** Agent Studio, Agent SDK, Voice, Live Assist, Insights
- **Notable:** Reached $150M ARR within roughly two years of founding, Crossed $15B valuation eight months after a $10B round, Won deployments at one in three of the world's largest banks

## Products & services

- **Agent Studio** — Visual environment for designing, testing, and deploying conversational AI agents.
- **Agent SDK** — Developer toolkit for building custom agents with code, tools, and integrations.
- **Voice** — Real-time voice agents that handle phone-based customer interactions.
- **Live Assist** — AI co-pilot that supports human agents during live conversations.
- **Insights** — Analytics layer that surfaces conversation trends, drop-offs, and resolution data.
- **Ghostwriter** — Agent-as-a-service tool that builds and deploys other agents from a natural-language brief.

## Achievements

- Reached $150M ARR within roughly two years of founding
- Crossed $15B valuation eight months after a $10B round
- Won deployments at one in three of the world's largest banks
- Launched Ghostwriter in April 2026, an agent that builds agents

## Latest updates

- **2026-05** — Closed $950M Series E at a $15.8B valuation led by Tiger Global and GV.
- **2026-04** — Launched Ghostwriter, an agent-as-a-service tool.
- **2026-02** — ARR reached $150M, up from $100M in November 2025.
- **2025-09** — Raised $350M at a $10B valuation led by Greenoaks.

## Links

- Website: https://sierra.ai
- LinkedIn: https://www.linkedin.com/company/sierra
- Twitter/X: https://x.com/sierraplatform
- YouTube: https://www.youtube.com/@Sierra-Platform

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Profile page: https://yespress.io/sierra
Published by YesPress — https://yespress.io
Last updated: 2026-05-23