Cresta vs Sierra
Cresta and Sierra are both enterprise-only, sales-led, cloud-only autonomous support agents, so the access-model split that separates most of this category separates nothing here — what separates them is that Cresta sells a whole contact-center suite in which five of its twelve products exist to make HUMAN agents better, while every one of Sierra's nine platform components is about the AI agent, and the two price on opposite sides of the risk: Cresta on inputs (agent count, conversation volume, channels), Sierra on outcomes (a rate per successful resolution, escalations free).
On this page
Cresta and Sierra both sell an autonomous AI agent to large enterprises, both are cloud-only and closed-source, and neither publishes a price or lets you sign up without talking to sales. The access-model question that separates most agents in this category — self-serve versus enterprise — separates nothing here. What separates them is what else is in the box, and read side by side on 2026-08-17 the difference is not subtle. Cresta's own page for AI assistants lists twelve products: AI Agent, Agent Assist, Conversation Intelligence, AI Analyst, Quality Management, Coach, Insights, Knowledge Agent, Opera, Agent Operations Center, Automation Discovery and Real-Time Translation. At least five of those — Agent Assist, Coach, Quality Management, Conversation Intelligence and the Agent Operations Center — exist to make human agents better, not to replace them. Sierra's platform page names nine components: Agent SDK, Agent Studio, Ghostwriter, Horizon, Context Engine, Insights, Explorer, Channels, and Trust and Reliability. Every one is about building, deploying or measuring the AI agent. Sierra ships nothing for the people on your floor.
The second difference is who carries the risk when the agent does not resolve the conversation. Sierra states its model in one line on its home page: you “only pay for the value Sierra delivers with outcome-based pricing” — a pre-negotiated rate per successful resolution, with escalations to a human not charged. Cresta states the opposite structure just as plainly: “Pricing is custom and based on deployment scope (products, agent count, conversation volume, channels, language coverage). There is no public self-serve tier.” Those are input dimensions, not outcomes. The one Cresta price that is public makes it concrete — its AWS Marketplace listing for Agent Assist, read live on 2026-08-17, sells Chat at $150,000 for twelve months against a cap of 125,000 chats with $1.20 per chat beyond it, or Voice at $150,000 against 100,000 calls with $1.50 per call beyond it, and the vendor's own refund policy on that listing reads “all subscriptions are non-cancellable and non-refundable for the period subscribed.” That is a price per conversation touched, not per problem solved. Neither model is a trick — Cresta's buys a suite, Sierra's buys a result — but they put the risk of a disappointing containment rate on opposite sides of the table.
On raw capability they are closer than the pricing suggests, and both publish enough to check. Cresta AI Agent runs voice, chat and SMS across more than 30 languages, and Cresta names three customer outcomes with numbers attached: Snap Finance at 5.5x higher containment and 23% higher CSAT, Xanterra at 74% containment and a $3.3M revenue lift, and Propel Holdings at 58% containment. Sierra runs chat, SMS, WhatsApp, email, voice and ChatGPT as a channel, and states 58 languages. Compliance is where they genuinely diverge. Sierra achieved FedRAMP High on 2026-06-10 in partnership with Knox Systems, the bar for cloud vendors serving US federal agencies; Cresta's own compliance list — ISO/IEC 42001, which it claims to be the first customer-experience AI provider to hold, plus SOC 2 Type II, HIPAA, GDPR, TISAX, CCPA and PCI-DSS alignment — does not name FedRAMP. Scale favours Sierra sharply: roughly $1.585B raised including a $950M round in May 2026 at a valuation above $15B, against Cresta's $280M+ and a $125M Series D in November 2024. Cresta is the older company, though — a 2017 Stanford AI Lab spinout with 500+ employees, against Sierra's founding in early 2024.
How Cresta and Sierra compare
| Feature | Cresta★ Our pickVisit Cresta ↗ | SierraVisit Sierra ↗ |
|---|---|---|
| Description | Unifies an autonomous AI Agent, real-time human Agent Assist and Conversation Intelligence on one contact-center platform, enterprise, custom-quoted, no self-serve tier. | Bret Taylor’s enterprise agent platform, branded AI agents that resolve customer issues end to end, priced on outcomes. |
| Category | Support agents | Support agents, Agent platforms |
| Pricing | $150,000 / year (12-month contract) | Custom |
| API | Yes | - |
| Tags | ||
| Pricing model | usage-based | usage-based |
| Free tier | No | No |
| Model / LLM | Not publicly disclosed (managed, multi-model stack) | Multiple frontier models (managed) |
| Interface | Web | Visual |
| Public API | Yes | - |
| Open source | No | No |
| Deployment | Cloud | Cloud |
| Limitations |
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Who each one is for
Verdict: Cresta or Sierra?
Pick Cresta if your contact center still has people in it. That is the whole verdict and it is not a hedge. Cresta is the only one of these two that sells you anything for your human agents — real-time Agent Assist, Coach, Quality Management, Conversation Intelligence and real-time translation, all on the same conversation record as the AI Agent deflecting the routine half. If your realistic plan is “automate what we can and make the remaining agents better,” Sierra sells the first half and nothing at all for the second: its Insights and Explorer measure its own agent's behaviour, not your workforce's. Being on this shortlist at all is usually the tell, because Cresta is sold into contact centers that have agents to assist.
Pick Sierra if you are buying resolutions rather than a platform, and there are three specific cases where it is the clearly better buy. First, if you cannot yet predict how much of your volume an AI agent will actually contain: Sierra's outcome pricing puts that risk on the vendor, where Cresta's only published SKU charges $150,000 a year against a conversation cap plus $1.20 to $1.50 per conversation over it regardless of what happened in the conversation. Second, if you are a US federal agency or bound to FedRAMP High by contract — Sierra has held it since June 2026 and Cresta's own compliance page does not claim it, so this stops being a preference. Third, if your human agents already live on a helpdesk you are not replacing, in which case most of Cresta's suite is product you will pay for and not use.
Stated as the two mistakes: buying Cresta with no meaningful human support team means paying for an assist-and-coaching suite to get a deflection engine. Buying Sierra for a 2,000-seat contact center that will still have 1,500 seats in two years means discovering you need a second vendor for assist, QA and coaching.
The digest
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Frequently asked questions
- Are Cresta and Sierra actually competing for the same buyer?
- Partly. Both sell an autonomous AI agent that resolves customer conversations end to end, both are enterprise-only and sales-led, and both are routinely shortlisted together for large contact-center deals. But they are not the same product: Cresta is a full contact-center platform whose twelve products include Agent Assist, Coach and Quality Management for human agents, while Sierra's nine platform components are all about the AI agent. A buyer with no human support team is comparing the wrong two things.
- Which one is cheaper?
- Neither publishes enough to answer that, and the two do not price on the same unit. Cresta states pricing is custom and based on deployment scope — products, agent count, conversation volume, channels and language coverage — with no public self-serve tier; its only public number is an AWS Marketplace listing for Agent Assist alone at $150,000 per twelve months for one channel (up to 125,000 chats or 100,000 calls, then $1.20 per chat or $1.50 per call), non-cancellable and non-refundable. Sierra publishes no price at all, only the model: a pre-negotiated rate per successful resolution, with escalations to a human not charged. The real difference is the unit, not the number — you pay Cresta per conversation handled and Sierra per problem solved.
- Does Sierra have anything for human agents?
- No product aimed at them. Sierra's platform page (read 2026-08-17) lists Agent SDK, Agent Studio, Ghostwriter, Horizon, Context Engine, Insights, Explorer, Channels and Trust and Reliability — agent-building, agent-deployment and agent-measurement tools. Its Insights, Explorer and Monitors analyse how Sierra's own agent performed, not how your staff performed. If you need real-time guidance, automated QA scoring or coaching for a human workforce, that is a separate vendor alongside Sierra, and it is included in Cresta.
- Which one can a US federal agency buy?
- Sierra, on the certification. It achieved FedRAMP High on 2026-06-10 through a partnership with Knox Systems, covering voice, chat and email in 58 languages. Cresta publishes ISO/IEC 42001 — claiming to be the first customer-experience AI provider to hold it — plus SOC 2 Type II, HIPAA, GDPR, TISAX, CCPA and PCI-DSS alignment, and its own compliance list does not name FedRAMP. That is what Cresta publishes rather than a confirmed absence, so a federal buyer should ask Cresta directly; but as of 2026-08-17 only Sierra can point at the authorization.
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