Sierra
Also known as: Sierra AI
Enterprise-grade conversational AI agent platform for customer experience.
Sierra is an enterprise conversational AI platform that builds branded, autonomous customer-experience agents. Founded in 2023 by Bret Taylor (former co-CEO of Salesforce and current chair of OpenAI's board) and Clay Bavor, who previously led Google Labs and Google's VR efforts, the San Francisco company has become one of the fastest-growing names in enterprise software, crossing $100M in ARR in under two years (reportedly $150M+ by early 2026) and counting more than 40% of the Fortune 50 among its customers, including Prudential, Cigna, Blue Cross Blue Shield, and Rocket Mortgage.
The platform, branded Agent OS, lets companies build, test, deploy, and continuously improve AI agents that operate across chat, voice, email, SMS, and WhatsApp in 30+ languages. Its model-agnostic 'constellation' architecture orchestrates multiple LLMs (OpenAI, Anthropic, Google, Meta) per task. Agent OS 2.0 spans roughly eight products, including Agent Studio for configuration (with no-code Journeys, Workspaces, and an Integration Library), an Agent Data Platform for persistent memory and context, and Live Assist for human escalation. As the first Level 1 PCI-compliant conversational AI platform, Sierra's agents can complete end-to-end commercial transactions (collections, renewals, and purchases), not just resolve support tickets.
In March 2026 Sierra launched Ghostwriter, an 'agent that builds agents': a business user describes what they need in plain English, or uploads SOPs, transcripts, and recordings, and Ghostwriter generates a production-ready agent, lowering the barrier to deployment for non-technical teams. Sierra prices on outcomes, charging only when an agent resolves an issue, saves a cancellation, or completes an upsell. It has raised over $1.58 billion total, most recently a $950 million Series E (May 2026) led by Tiger Global and GV at a $15.8 billion valuation.
Vendor details
Canonical URL
https://sierra.ai
Category
Customer support agent
Subcategory
Enterprise conversational AI / customer experience agent platform
Funding status
$1.58B+ raised over 4 rounds. $950M Series E (May 2026) led by Tiger Global and GV (Google Ventures) at a $15.8B post-money valuation; prior $350M at $10B (Sept 2025) and $175M at $4.5B (Oct 2024). Reported $150M+ ARR; crossed $100M ARR in under two years. ~165 employees.
Company status
independent
Use cases & customers
Primary use cases
Target customers
Deployment options
Integrations
Model-agnostic 'constellation' architecture orchestrating multiple LLMs (OpenAI, Anthropic, Google, Meta) per task. Operates across chat, voice, email, SMS, and WhatsApp in 30+ languages, with native contact-center integration and distribution through ChatGPT. A declarative Agent SDK plus Agent Studio's Integration Library connect to enterprise systems; the platform is Level 1 PCI-compliant, enabling end-to-end commercial transactions.
In practice
Your support agent can answer questions but can't actually complete a transaction. Sierra is PCI Level 1 compliant, so its agents handle collections, renewals, and purchases end to end, not just tickets.
Building a production agent usually needs engineers. Sierra's Ghostwriter takes a plain-English description or your SOPs and transcripts and generates a production-ready agent.
You'd rather pay for results than software seats. Sierra prices on outcomes, charging when an agent resolves an issue, saves a cancellation, or completes an upsell.
Sources & related URLs
Agentic Index coverage score
12.0 / 14 capabilities · 86%
| Integrations & Tool CallingRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
|---|---|
| Workflow OrchestrationRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Knowledge Grounding & RAGNative RAG and Agent SDK; connector catalog not fully documented publicly | Full |
| Human Oversight & GuardrailsRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Security, Identity & GovernanceRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Observability & AuditabilityRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Memory & State PersistenceRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Deployment & Data ResidencyBroad omnichannel deploy and prebuilt skills; SaaS-only with limited public detail | Partial |
| Prebuilt Agents, Templates & PacksBroad omnichannel deploy and prebuilt skills; SaaS-only with limited public detail | Partial |
| Triggers & Channel CoverageRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Model Flexibility & RoutingRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| APIs, SDKs & MCP ExtensibilityNative RAG and Agent SDK; connector catalog not fully documented publicly | Full |
| Testing, Debugging & OptimizationRe-validated from Sierra Agent OS docs and 2026 public reviews | Full |
| Browser & Computer UseConversational agents act via API integrations; no browser or computer-use control documented | Unable to verify |
The Agentic Index coverage score grades every vendor Full, Partial or Unable to verify against the same 14 buyer facing capabilities, from public evidence only. Each capability links to how all vendors in the index score on it. How this evidence is graded
Recent platform changes
Sierra introduced Agency, a new infrastructure primitive that provides secure and scalable sandboxes for its AI agents. The Agency environment allows agents to execute long-running, complex tasks with dedicated computing resources, maintaining state and data isolation without interruption.
Bears on: Agent capability
View sourceSierra acquired the AI startup Takeoff and introduced the Horizon Agent Platform. This new offering focuses on long-horizon AI agents designed to execute end-to-end tasks across sectors like lending and healthcare, rather than being limited to single-turn customer support conversations.
Bears on: Agent capability
View sourceSierra announced FedRAMP High certification, making its agent platform available for U.S. federal-agency deployment.
Bears on: Security / enterprise
View sourcePricing
Outcome-based (per resolution) · contact sales
outcome-based (per resolution/outcome)
What is public
Sierra prices on outcomes: customers are charged only when an agent resolves an interaction, saves a cancellation, or completes an upsell, with no per-seat fees. Pricing is sales-led and not publicly listed. Third-party reports and procurement filings estimate effective costs of roughly $0.50 to $2.00 per resolved conversation, translating to six-figure annual commitments that generally exclude SMB and most mid-market buyers.
Variable cost rationale
Charged per successful outcome (resolution, saved cancellation, completed upsell), so total cost scales directly with resolved volume. Third-party estimates cite roughly $0.50 to $2.00 per resolved conversation.
Sales call required
Yes, required for paid access
Commercial notes
Founded 2023 by Bret Taylor and Clay Bavor. Reached $150M+ ARR by early 2026 and raised a $950M Series E (May 2026) at a $15.8B valuation. More than 40% of the Fortune 50 among its customers.
Key ambiguities
No public per-resolution or per-seat rate. Figures are third-party estimates and vary by scope.
Missing data
Sierra does not publish per-resolution or per-seat pricing. Estimates come from integration partners and procurement filings.
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Alternatives to Sierra
The closest documented capability profiles to Sierra among customer support agents tracked by Agentic Index, ordered by similarity on the same 14 point evidence the rankings use. No vendor pays for placement.
- ASAPP11.0 / 14A lighter documented profile than Sierra
- Infobip12.0 / 14Fuller documented coverage on Prebuilt Agents, Templates & Packs
- Kustomer11.0 / 14A lighter documented profile than Sierra
- NICE CXone13.0 / 14Adds documented Browser & Computer Use
- Quiq12.0 / 14Fuller documented coverage on Prebuilt Agents, Templates & Packs
- SleekFlow11.0 / 14A lighter documented profile than Sierra
Similarity is computed from each vendor's Agentic Index coverage score evidence, axis by axis, not from the totals. How this evidence is graded