Sierra
7.4/10Sierra is an enterprise conversational AI platform that builds and runs customer service agents across chat, voice, SMS, WhatsApp and email.
Data last updated November 2026 · Our methodology
Overview
Sierra is a San Francisco company founded in 2023 by Bret Taylor and Clay Bavor. It builds AI agents that large consumer brands use to handle customer conversations. One agent can run across chat, phone, SMS, WhatsApp, email and ChatGPT. It can look up answers in company policies and FAQs, and it can act in back-end systems, for example by changing a subscription or filing a warranty claim. When a conversation needs a person, it hands over to a human agent with a summary. Teams can build agents in three ways. Agent Studio is a no-code builder for customer experience teams. The Agent SDK lets engineers define customer journeys as code. Ghostwriter creates or edits agents from SOPs, call transcripts or plain-language goals and runs simulations on each change. The Insights tools add conversation exploration, monitors, A/B experiments and tracing. Customers include SiriusXM, ADT, Rocket Mortgage, SoFi, Rivian and Discord. Pricing is outcome-based and there is no public price list. Customers sign an annual platform contract and then pay per outcome, such as a resolved conversation or a saved cancellation. Unresolved conversations are usually not charged. Sierra also sells through AWS Marketplace, and its customer context features connect to Snowflake, Databricks, Google Cloud, AWS and Redis. The main limitation is access. There is no self-serve tier, and implementation is largely run by Sierra's own team. Competitor estimates put contracts in the six figures a year, which leaves out small companies.
Our Rating
Who Sierra is best for
Good fit
Built for customer service agents that resolve conversations across channels and hand off to human agents.
Sierra sells annual contracts to large consumer brands and holds compliance certifications such as FedRAMP and HIPAA.
Customers include Rocket Mortgage and SoFi, and it holds PCI DSS compliance.
Less suited
The Agent SDK lets engineers define customer journeys as code.
It lists HIPAA compliance, but no healthcare customers are named.
Larger mid-market firms can buy, but estimated six-figure contracts and the lack of a self-serve tier make it hard to justify.
It lists FedRAMP, but no public sector customers are named.
Some venture-backed tech companies such as Ramp and Discord are customers, but costs are high for early-stage teams.
Contracts are estimated at about 150,000 USD or more, with no self-serve tier.
There is no self-serve plan and no public pricing, so it is effectively out of reach.
Pros & Cons
Pros
- Outcome-based billing means customers usually pay only for resolved conversations or other agreed results, not for each seat.
- Three build options cover both CX teams and engineers: the no-code Agent Studio, the code-first Agent SDK, and Ghostwriter for building agents from SOPs.
- One agent runs across chat, voice, SMS, WhatsApp, email and ChatGPT, keeping context between channels.
- Its list of compliance attestations is broad, covering SOC 2, ISO 27001, ISO 42001, HIPAA, PCI DSS and FedRAMP.
- It has a strong roster of enterprise customers, including SiriusXM, ADT, Rocket Mortgage and SoFi.
Cons
- There is no public pricing, and competitor estimates put annual contracts at about $150,000 or more.
- There is no self-serve or trial tier, so small teams cannot try it on their own.
- Implementation is largely vendor-led, which can make customers depend on Sierra's team for changes.
- There are few public reviews (7 on Gartner Peer Insights) to verify claims against.
- Some reviewers say voice quality still falls short of human level, and that complex telephony setups depend on how far the integration goes.
Key Features
Sierra Pricing
Sierra Platform (enterprise contract)
- 12-month platform contract
- Agent Studio, Agent SDK and Ghostwriter
- Usually no charge for unresolved conversations
- Outcome-based usage fees on top of the contract
- Chat, voice, SMS, WhatsApp, email and ChatGPT channels
Frequently Asked Questions
Customers sign an annual platform contract and then pay per outcome on top of it, such as a resolved conversation, a saved cancellation or an upsell. Unresolved conversations are generally not charged.
No. Sierra sells through its sales team and AWS Marketplace on enterprise contracts.
Chat, voice or phone, SMS, WhatsApp, email and ChatGPT, all from a single agent.
Not always. Agent Studio and Ghostwriter are designed for non-technical CX teams, while the Agent SDK lets engineers build journeys as code.
Sierra lists SOC 2, ISO 27001, ISO 42001, HIPAA, GDPR, PCI DSS and FedRAMP, and it publishes a trust center.
The Insights suite includes conversation exploration, monitors for flagging conversations, multivariate experiments and traces of agent actions.
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