Sierra
Category: AI Agents
An AI-powered conversational agent platform for building and deploying enterprise-grade customer service bots. Sierra was founded in 2023. The company is led by Bret Taylor. Based in San Francisco Bay Area, CA & Remote. Team size: 51-200 (estimated, not officially disclosed). Total funding raised: $285 million. Latest round: Series C ($350.0M, 2025-09) - Sierra. Key investors include ["Greenoaks Capital","ICONIQ Growth","Thrive Capital","Sequoia Capital","Benchmark"].
- Founded
- 2023
- Headquarters
- San Francisco Bay Area, CA & Remote
- Team size
- 51-200 (estimated, not officially disclosed)
- Total funding
- $285 million
Value proposition
Automates complex customer service tasks end-to-end, reduces AI hallucinations using a multi-model approach, and offers customizable brand-aligned personalities.
Products and solutions
["Generative AI-powered conversational agents","Integration layer connecting multiple large language models (from OpenAI, Anthropic, Meta, etc.)"]
Unique value
Utilizes a 'constellation' of multiple large language models to cross-check for accuracy and reduce hallucinations. Offers deep customization of the AI agent's personality to align with brand identity.
Target customer
Large enterprises requiring sophisticated, automated customer service solutions.
Industries served
["Health & Wellness","Media & Entertainment","Consumer Services","Home Security","Retail"]
Technology advantage
Deep integration with enterprise backend systems to perform actions, not just provide answers. The leadership team's extensive experience at top tech companies (Salesforce, Google, Facebook).
How they differentiate
Focuses on premium, action-oriented automation rather than just Q&A. Claims significantly lower hallucination rates due to its multi-LLM architecture.
Main competitors
["Ada","Intercom","Zendesk"]
Key partnerships
["OpenAI","Anthropic","Meta"]
Notable customers
["WeightWatchers","Sirius XM","Sonos","ADT","Casper"]
Major milestones
["Launched publicly in February 2024 after operating in stealth mode.","Announced raising $110 million in combined seed and Series A funding in February 2024.","Secured a $175 million Series B funding round in October 2024, reaching a $4.5 billion valuation.","Onboarded major enterprise clients including WeightWatchers, SiriusXM, Sonos, and ADT."]
Growth metrics
Reached a $4.5 billion valuation following its Series B round in October 2024.
Market positioning
A premium, high-end solution targeting large, complex enterprises.
Geographic focus
Primarily US-based, serving global brands.
Patents and IP
Information not publicly available
About Bret Taylor
Bret Taylor is a distinguished software engineer and industry leader with a 20-year history of building widely-used products. He is the co-founder and CEO of Sierra, a conversational AI platform. Previously, he was the Co-CEO of Salesforce. He also founded Quip, which was acquired by Salesforce. Before that, he was the CTO of Facebook and started his career at Google, where he co-created Google Maps. He also serves as the chairman of the board at OpenAI.
Official website: https://sierra.ai/