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Sierra is a conversational AI company that builds AI-powered customer experience agents for businesses. Founded in 2023 by Bret Taylor, the former co-CEO of Salesforce, and Clay Bavor, a longtime Google executive, Sierra has grown into one of the fastest-scaling enterprise software companies in history. The company reached $100 million in annual recurring revenue (ARR) within seven quarters of its public launch in February 2024, and crossed $150 million in ARR by early 2026. Sierra is headquartered in San Francisco and has raised a total of $635 million in venture funding at a $10 billion valuation as of September 2025.
Sierra's platform, called Agent OS, enables companies to deploy autonomous AI agents that handle customer interactions across text, voice, email, SMS, and other channels. Rather than serving as simple chatbots, Sierra's agents can take actions within business systems, such as processing orders, managing subscriptions, originating mortgages, and handling returns. The company serves hundreds of enterprise customers across industries including financial services, healthcare, retail, telecommunications, and media.
Sierra was co-founded in 2023 by Bret Taylor and Clay Bavor. The two first met while working together at Google in the mid-2000s and reconnected years later at a restaurant in Palo Alto. Both had recently left senior leadership positions at major technology companies. Taylor had stepped down as co-CEO of Salesforce at the end of January 2023, while Bavor had departed Google in early 2023 after 18 years at the company.
The founders recognized that large language models and generative AI were creating a new paradigm for how businesses could interact with their customers. They believed that conversational AI would become as transformative as mobile apps and websites had been for previous generations of customer engagement. As Taylor and Bavor wrote in their launch announcement, "In the age of conversational AI, the best customer experience is not installing an app or clicking a link, but simply having a conversation."
Sierra emerged from stealth on February 13, 2024, simultaneously announcing its product and a $110 million funding round. At the time of launch, the company had already been working with several major brands. Four initial customers were highlighted: WeightWatchers, SiriusXM, Sonos, and OluKai. The WeightWatchers deployment was already handling roughly 70% of customer sessions with a 4.6 out of 5 customer satisfaction rating.
Sierra's growth trajectory accelerated throughout 2024 and into 2025. The company expanded its customer base from a handful of launch partners to hundreds of enterprise clients. In October 2024, Sierra launched its voice product, enabling AI agents to handle inbound and outbound phone calls. Voice interactions grew so rapidly that, less than a year after launch, phone calls overtook text as the primary channel for Sierra's agents.
By November 2025, Sierra announced it had reached $100 million in ARR in just seven quarters, placing it among the fastest enterprise software companies to hit that milestone. The company followed this with its first $50 million quarter, entering its third year with over $150 million in ARR.
Sierra has expanded well beyond its San Francisco headquarters. The company maintains offices in nine cities: San Francisco, New York, Atlanta, London, Singapore, Tokyo, Paris, Madrid, and Toronto. In November 2025, Sierra expanded into France to support European customers, and in March 2026, the company opened its Madrid office. As of February 2026, Sierra employs approximately 600 people.
Bret Steven Taylor (born July 10, 1980) serves as co-founder and CEO of Sierra. Taylor holds bachelor's and master's degrees in computer science from Stanford University, which he earned in 2002 and 2003 respectively.
Taylor began his career at Google, where he co-created Google Maps, one of the company's most widely used products. He left Google in 2007 to join Benchmark Capital as an entrepreneur-in-residence, where he co-founded FriendFeed, a social networking service. FriendFeed is credited with pioneering the "Like" button concept that later became a defining feature of social media. Facebook acquired FriendFeed in 2009 for approximately $50 million, and Taylor subsequently became Facebook's chief technology officer, a role he held until 2012.
After leaving Facebook, Taylor founded Quip, a collaborative productivity software company. Salesforce acquired Quip in 2016 for $750 million. Taylor joined Salesforce as chief product officer in 2017, was promoted to president and chief operating officer in 2019, and was named co-CEO alongside Marc Benioff in November 2021. He stepped down from the co-CEO role at the end of January 2023.
In addition to leading Sierra, Taylor serves as chairman of the board of OpenAI, a position he assumed in November 2023 as part of a reconstituted board following the brief ouster of CEO Sam Altman. Taylor has stated that his role at OpenAI focuses on governance rather than day-to-day operations, and that Sierra is a customer of OpenAI rather than a competitor.
| Role | Organization | Period |
|---|---|---|
| Software Engineer / Co-creator of Google Maps | 2003-2007 | |
| Co-founder and CEO | FriendFeed | 2007-2009 |
| Chief Technology Officer | 2009-2012 | |
| Founder and CEO | Quip | 2012-2016 |
| CPO, then President/COO, then Co-CEO | Salesforce | 2017-2023 |
| Co-founder and CEO | Sierra | 2023-present |
| Chairman of the Board | OpenAI | 2023-present |
Clay Bavor serves as co-founder and president of Sierra. Bavor spent 18 years at Google, joining the company in 2005. Over his tenure, he held a series of increasingly senior roles spanning product management, design, and emerging technology.
At Google, Bavor oversaw product and design for Gmail, Google Drive, Google Docs, and Google Apps for Work (later renamed Google Workspace). In 2016, Google appointed him vice president of its virtual reality division, where he led the launch of the Daydream VR platform. He also started and directed Google's augmented reality initiatives, Google Lens, and Project Starline, a holographic videoconferencing system.
In November 2021, Google reorganized several forward-looking projects into a new division called Google Labs, which reported directly to CEO Sundar Pichai. Bavor was named to lead this organization, which encompassed Google's AR and VR efforts, Project Starline, and Area 120, the company's internal incubator. Bavor departed Google in early 2023 to co-found Sierra.
| Role | Organization | Period |
|---|---|---|
| Product Manager / VP of Product and Design | Google (Gmail, Drive, Docs, Workspace) | 2005-2016 |
| VP of Virtual Reality | 2016-2021 | |
| Head of Google Labs | 2021-2023 | |
| Co-founder and President | Sierra | 2023-present |
Sierra has completed three major funding rounds, raising a cumulative $635 million. The company's valuation has grown from approximately $1 billion at its public debut to $10 billion in under two years.
| Round | Date | Amount | Valuation | Lead Investor(s) | Other Notable Investors |
|---|---|---|---|---|---|
| Seed | February 2024 | $110 million | ~$1 billion | Sequoia Capital, Benchmark | ICONIQ, Thrive Capital |
| Series B | October 2024 | $175 million | $4.5 billion | Greenoaks Capital | ICONIQ, Thrive Capital |
| Series C | September 2025 | $350 million | $10 billion | Greenoaks Capital | Existing investors |
Sequoia Capital partner Ravi Gupta and Benchmark partner Peter Fenton both joined Sierra's board of directors following the initial round. Greenoaks Capital, which led both the Series B and Series C rounds, has been a consistently active backer of the company.
The rapid escalation in valuation reflects Sierra's revenue growth and the broader market enthusiasm for AI agents in enterprise settings. Between the Series B in October 2024 and the Series C in September 2025, Sierra's valuation more than doubled from $4.5 billion to $10 billion.
Sierra's core product is Agent OS, a platform for building, managing, and optimizing AI-powered customer experience agents. Agent OS supports both no-code and programmatic agent development, allowing business users and engineers alike to create and configure agents.
The platform consists of several components:
Agent Studio provides a no-code interface for configuring customer journeys, knowledge bases, and brand guidelines. Agent Studio 2.0, announced at Sierra Summit in 2025, introduced three key capabilities: Journeys (a natural language interface for defining customer experience goals), Workspaces (collaborative development environments modeled after GitHub), and Integrations (connectors to back-end systems that can be configured in minutes).
Agent SDK offers a developer-focused framework for programmatically defining agent goals, guardrails, and composable skills. This gives engineering teams fine-grained control over agent behavior and allows for custom fine-tuning.
Insights is an analytics and observability layer for measuring agent performance, running experiments, and understanding every decision an agent makes. Insights 2.0 added real-time performance optimization recommendations.
Voice enables agents to handle inbound and outbound phone calls with natural-sounding speech. Sierra launched Voice Sims in 2025, a testing tool that simulates real-world calls to train and validate voice agents before they interact with live customers.
Live Assist augments human support representatives with real-time AI guidance, auto-drafted responses, and one-click actions. This allows organizations to blend AI and human support seamlessly.
Agent Data Platform (ADP) serves as the memory and intelligence layer for Sierra's agents. ADP unifies conversation data with structured customer information from billing, inventory, and transaction systems, enabling agents to greet customers by name, remember prior conversations and preferences, and take proactive action.
A distinctive feature of Sierra's technical approach is its "constellation of models" architecture. Rather than relying on a single large language model, Sierra's agents use 15 or more frontier, open-weight, and proprietary models, each selected for specific tasks. The system identifies four primary task categories and routes work to the most suitable model:
| Task Category | Description | Optimization Priority |
|---|---|---|
| Low-latency tool calling | Straightforward operations like order lookups and inventory checks | Speed |
| High-precision classification | Detecting behavioral nuance and intent | Accuracy |
| Long-context reasoning | Processing dense information without hallucination | Reliability |
| Tone generation | Producing brand-appropriate, empathetic responses | Quality |
Sierra's orchestration layer decomposes agent behavior into modular, isolated capabilities and routes requests to appropriate models automatically. The system includes built-in redundancy across model providers, continuously monitoring latency, error rates, and timeouts. When degradation occurs with one model, the platform fails over to healthier alternatives. As new frontier models emerge, agents can automatically benefit through prompt adjustments rather than requiring complete rebuilds.
Sierra treats agent safety as a systems problem rather than a single-point solution. The company acknowledges that LLMs are inherently non-deterministic and that at enterprise scale, even rare error rates produce visible failures. Sierra's approach focuses on achieving bounded error rates through layered defenses.
The safety architecture employs multiple specialized supervisory agents, internally described as "Jiminy Crickets," each with a distinct safety responsibility:
The system applies graduated strictness levels depending on the type of interaction. Responses to adversarial or illegal inputs receive maximum adherence to safety rules, while conversational phrasing in routine interactions permits more latitude for natural dialogue.
Sierra maintains compliance certifications including SOC 2, HIPAA, GDPR, CCPA, CSA STAR, ISO 27001, and ISO 42001.
At Sierra Summit in 2025, the company announced Agent OS 2.0, which introduced eight new products built around three major transitions:
Multi-channel to single agent: Agents can now be deployed across chat, voice, email, SMS, ChatGPT, and contact centers from a single build. Sierra added one-click publishing to ChatGPT and introduced Live Assist for guiding human support teams in real time.
Technology to product: Agent Studio 2.0 made agent building accessible to non-engineers through natural language configuration, collaborative workspaces, and rapid system integrations.
Conversations to relationships: The Agent Data Platform transformed agents from handling isolated conversations into building lasting customer relationships through memory, context, and proactive engagement.
Sierra serves hundreds of enterprise customers spanning multiple industries. The company reports that 25% of its customers have revenue exceeding $10 billion, and over 50% have revenue above $1 billion. Sierra's agents handle customer interactions at a scale that the company describes as reaching over 95% of American shoppers, more than 50% of U.S. families in healthcare, over 70% of the fintech value chain, and 25% of European banking.
| Industry | Customers | |---|---|---| | Financial Services | SoFi, Ramp, Brex, Chime, Rocket Mortgage, Marshmallow | | Healthcare | Cigna, Sutter Health, Pendulum, AG1 | | Retail and Consumer | Sonos, OluKai, Casper, Thrive Market, Wilson, Chubbies, ThirdLove, Madison Reed, Minted, Sun & Ski Sports, Vans, Gap, Bissell, ScottsMiracle-Gro | | Media and Entertainment | SiriusXM, DIRECTV, Tubi, Vivid Seats, Discord | | Technology | Redfin, CDW, Rivian, CLEAR, Wayfair, RunBuggy | | Telecommunications | Singtel | | Home Services and Security | ADT, Safelite | | Wellness | WeightWatchers | | Workforce and Education | Guild |
Several Sierra deployments have produced publicly cited results:
Sierra operates as a business-to-business software platform, selling its Agent OS to enterprises on a subscription basis. The company charges based on usage and the scope of agent deployment. Sierra positions itself not as a replacement for human customer service teams but as a complement that handles routine interactions at scale while freeing human agents to focus on situations that require judgment and empathy.
The company announced plans to expand beyond customer service into sales and engagement use cases, broadening its addressable market.
Sierra operates in the growing market for enterprise conversational AI and AI-powered customer service. The company competes with a range of players, from established customer service platforms adding AI capabilities to newer AI-native startups.
Key competitors include Intercom (with its Fin AI agent), Decagon, Forethought, Cognigy, Kore.ai, and PolyAI. Sierra differentiates itself through its multi-model architecture, its focus on enabling agents to take actions within business systems (not just answer questions), and the track record of its founding team in building enterprise-scale products.
The broader market for AI-powered customer service is expanding rapidly. Industry data from 2025 suggests that roughly 40% of enterprises have deployed conversational AI systems, with another 40% actively evaluating options.
Sierra has articulated five core values that guide its operations:
| Value | Description | |---|---|---| | Trust | Building AI that is accessible, safe, and useful | | Customer Obsession | Focusing on business outcomes rather than technical metrics alone | | Craftsmanship | Emphasizing quality and attention to detail in every product | | Intensity | Playing to win while maintaining transparency about setbacks | | Family | Balancing high performance with support for employees' personal lives |
| Date | Event | |---|---|---| | 2023 | Bret Taylor and Clay Bavor co-found Sierra | | February 13, 2024 | Public launch; $110 million funding round announced (Sequoia, Benchmark) | | October 2024 | Voice product launched; $175 million Series B at $4.5 billion valuation (Greenoaks) | | September 2025 | $350 million Series C at $10 billion valuation (Greenoaks); Sierra Summit held; Agent OS 2.0 announced | | November 2025 | $100 million ARR milestone reached in seven quarters; expansion into France | | Early 2026 | ARR surpasses $150 million; employee count reaches approximately 600; Madrid office opens |