AI agents that resolve customer service requests across chat, email and phone.
Sales & Customer Support
Sierra
Builds and runs AI customer service agents for big brands, across chat, email and phone.
3.9our rating
Paid
Quick take
- Enterprise-grade AI agents that do real work, like processing a return or changing a booking, across chat, email and phone.
- No public pricing. You pay for outcomes (for example, a resolved conversation), and estimates put contracts well into six figures a year.
- Built for large brands; there is no free plan, trial or self-serve sign-up.
- Strong reputation and big-name customers, but few independent user reviews, so ask for references.
What is Sierra?
Sierra builds AI agents that talk to your customers on your behalf. One agent can work across website chat, SMS, WhatsApp, email, phone and even inside ChatGPT. Unlike a simple chatbot, it is connected to your systems, so it can change a booking, process a return, update an address or save a cancellation, following your own policies. You describe what the agent should do in plain English (or upload your scripts and call transcripts), and Sierra's tools build, test and monitor it.
Sierra was started by Bret Taylor (former Salesforce co-CEO and OpenAI's chair) and Clay Bavor (ex-Google), and is used by large brands such as SiriusXM, Wayfair, Gap, Rocket Mortgage and Discord. Pick it when you are a large company with millions of customer conversations and want a team to build and run a branded agent with you. Intercom, Zendesk and Ada are easier to buy and start with; Sierra is a bigger project with a bigger price.
The catch: there is no public price, no free trial and no self-serve sign-up. Third-party estimates put contracts in the six figures a year, plus setup. Public reviews are thin because most customers are large enterprises under contract. For a small or mid-sized business this is the wrong tool.
Who's using it, and who it's for
- Enterprise support teams
- Contact centres
- Retail brands
- Banks and insurers
- Telcos
Large consumer brands that want an AI agent to handle a big share of their customer conversations end to end.
Key features
Agent Studio
Where your team and Sierra's build, test and update the agent's goals, steps and guardrails.
Ghostwriter
Drafts an agent from your existing procedures, scripts or call transcripts, or from a plain-English description.
One agent, every channel
The same agent answers on chat, SMS, WhatsApp, email and voice calls.
Connected to your systems
Looks up orders and accounts and takes actions, following the rules you set.
Insights and testing
Monitoring, experiments and reports on what customers ask and how the agent performs.
How we rate it
3.9 / 5
Our rating
From using the tool ourselves. The average of the five scores.
- Ease of use
- 3.0
- Features
- 4.5
- Output quality
- 4.5
- Value for money
- 3.0
- Speed & reliability
- 4.5
How quickly someone non-technical gets value from it.
How completely it covers its own job, and how well the pieces fit together.
How good the results are before you fix them.
What you get for the price, including the free plan.
How fast it is and how often it falls over.
Sierra pricing
- Our pick
Enterprise
Custom
Large companies with high conversation volumes.
- Priced on outcomes, such as resolved conversations
- Build support from Sierra's team
- All channels, including voice
- Monitoring and analytics
Which plan should you pick?
There is one route: talk to Sierra's sales team. Agree clearly what counts as an outcome you pay for, and what setup and services cost, before you sign.
Prices in USD unless noted, checked 22 October 2026. Vendors change plans often, so confirm on their site before you buy.
Best use cases
Ways Sierra can slot into your week.
- 1
Handle returns and exchanges
Let the agent check the order, apply your returns policy and book the return without a human touching it.
- 2
Answer the phone
Put an AI voice agent on your support line to handle common calls and pass the rest to staff with a summary.
- 3
Save cancellations
When a customer wants to cancel, the agent offers the retention options you approve and records the outcome.
- 4
Change bookings and accounts
Customers update an address, booking or plan in a conversation instead of waiting in a queue.
How it fits your tech stack
It sits in front of your existing contact centre and helpdesk, connected to your CRM, order and billing systems so it can act. Human agents stay for the conversations it hands over.
Pros and cons
Pros
- Agents take real actions, not just answer questions
- Covers voice as well as chat, SMS, WhatsApp and email
- Outcome-based pricing means you pay for results, not seats
- Proven at very large brands
Cons
- No public pricing; estimates put it out of reach for most small and mid-sized businesses
- No trial or self-serve option, so you are committing to a sales process and a project
- Few independent reviews to check claims against
- You depend on Sierra's team for much of the build
Sierra alternatives
The closest alternatives to Sierra in the library, best rated first.
Intercom
4.2
Best for answering common customer questions automatically
Compare with Sierra
Hyperbound
4.1
Best for practising cold calls before going live
Compare with Sierra
Retell AI
4.1
Best for AI receptionist for a small business
Compare with Sierra
Yoodli
4.1
Best for rehearsing a pitch or presentation
Compare with Sierra
Why it made the list
It is one of the most talked-about enterprise AI agent companies, and well-known brands use it to run real customer service at scale.
Sierra FAQ
How much does Sierra cost?
Pricing isn't published; check the vendor's site for a quote. Prices checked 22 October 2026 against Sierra's pricing page.
Is Sierra free?
No. Pricing isn't published; check the vendor's site for a quote.
What is Sierra best for?
Sierra is best for high-volume customer service at large brands, AI phone agents that take real actions and Returns, bookings and account changes. Large consumer brands that want an AI agent to handle a big share of their customer conversations end to end.
What are the best Sierra alternatives?
The closest alternatives are Intercom, Hyperbound, Retell AI and Yoodli. Intercom is best for answering common customer questions automatically.
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