Sierra

What is Sierra?

Sierra is an enterprise conversational-AI platform for customer experience, co-founded by Bret Taylor (former co-CEO of Salesforce and chair of OpenAI’s board) and Clay Bavor (ex-Google). It lets large companies build branded AI agents that resolve customer issues end to end — answering questions, taking actions and completing tasks — across chat, email, SMS, WhatsApp, voice and ChatGPT. Rather than a self-serve tool, it is a managed ‘agent OS’ delivered to enterprises, and has become one of the most prominent names in the category. Founded in early 2024, Sierra has raised roughly $1.585 billion across four funding rounds in under two years — most recently a $950 million round in May 2026 led by Tiger Global and GV that pushed its valuation above $15 billion — and counts SoFi, Ramp and Chime among its customers. On 2026-06-10 it achieved FedRAMP High certification in partnership with Knox Systems, opening the door to the most sensitive US federal government workloads. On 2026-07-16, co-founders Taylor and Bavor announced Horizon, a platform layer for agents that proactively pursue a goal over days, weeks or months — such as originating a loan or securing a healthcare prior authorization — rather than resolving one conversation at a time.

What does Sierra do?

Sierra builds and operates customer-facing AI agents on behalf of enterprises. An agent is grounded in a company’s policies, systems and tone, and can hold a natural conversation, look up account data, and actually complete tasks, issuing a refund, changing a subscription, tracking an order, not just answer FAQs. Agents run across chat, email, SMS, WhatsApp, voice and ChatGPT from a single definition. Teams build and refine agents in Agent Studio, a visual environment, with Ghostwriter turning SOPs, transcripts or plain-English descriptions into production-ready agents, while developers can use the gated Agent SDK for deeper control. A supervision and analytics layer, Explorer, Monitors, Experiments and Observability, lets teams watch what agents do, catch issues proactively and A/B test changes, and an Agent Data Platform gives agents persistent memory and connects to warehouses like Snowflake and Databricks. Sierra is sold as a managed enterprise engagement rather than a public sign-up product, and prices on outcomes: you pay when an agent successfully resolves a customer’s issue, and escalations to a human are not charged.

Key features

• End-to-end resolution: Agents take real actions — refunds, subscription changes, order lookups — grounded in company policy, not just canned answers.
• Agent Studio + Ghostwriter: A visual builder plus a tool that turns SOPs, transcripts or plain English into production-ready, multilingual agents.
• Omnichannel from one definition: One agent spans chat, email, SMS, WhatsApp, voice and ChatGPT.
• Supervision & analytics: Explorer, Monitors, Experiments and Observability let teams watch behaviour, catch issues and A/B test changes.
• Horizon (long-horizon agents): A platform layer, launched July 2026, for agents that proactively pursue a goal over days or weeks — e.g. originating a loan or securing a healthcare prior authorization — instead of resolving a single conversation.

What are Sierra's use cases?

• Enterprise support at scale: A large brand deflects and resolves a high volume of customer conversations autonomously, escalating only edge cases to staff.
• Post-purchase account actions: The agent completes refunds, subscription changes and order tracking end to end by acting on connected systems.

What does Sierra integrate with?

• Data warehouses — Snowflake, Databricks
• Cloud — Google Cloud, AWS
• Channels — voice, WhatsApp, SMS, email, ChatGPT
• Business systems via connectors (CRM, commerce, order systems)
• Model Context Protocol (MCP) — Sierra agents are natively publishable to ChatGPT Apps via MCP

Why use Sierra?

• Backed by a top-tier team and adopted across large enterprises, Sierra reported $150M+ ARR by February 2026 and says it is used across more than 40% of the Fortune 50.
• Agents take real, end-to-end actions across every customer channel, not just answer questions.
• Outcome-based pricing aligns cost with resolved issues, and escalations to a human are not charged.

Pros & cons

Sierra pricing

• Outcome-basedCustom

See current pricing on sierra.ai ↗Compare Sierra alternatives →

Sierra review

Sierra is the enterprise standard-bearer for customer-experience agents, and the pedigree is real: co-founded by Bret Taylor and Clay Bavor, it reached $150M+ ARR by February 2026, has raised roughly $1.585 billion at a valuation above $15 billion, and is used across more than 40% of the Fortune 50. What sets it apart is depth, agents don’t just answer, they act, completing refunds and account changes across chat, voice, email and more, wrapped in serious tooling for building, supervising and testing them. Its outcome-based pricing (pay for resolutions, escalations free) is a genuinely aligned model. The flip side is access: it is sales-led with no public pricing, no free tier and a gated SDK, so it is neither quick to trial nor a fit for smaller teams. Pick Sierra if you are an enterprise that wants autonomous agents doing real work; skip it if you need self-serve, transparent pricing or an open API.

The Fortune-500 pick for agents that actually resolve, deep, credible and outcome-priced, but strictly enterprise, sales-led and opaque on price.

Frequently asked questions