Choose a Sierra alternative by how the agent learns your policies and how it hands a conversation to a person. Agent-first platforms focus on resolving issues automatically, voice-led tools cover phone support, and full customer service suites mix AI and human agents in one system. Run your own hardest tickets through each before deciding.
If you run support at a larger company, moving off Sierra is less about features and more about trust: will a new agent follow your rules, and will it know when to step aside? Here are nine alternatives, in no particular order, starting with a summary table.
Nine AI agent platforms in brief
| Tool | Platform type | Built for |
|---|---|---|
| Crescendo | AI-native CX platform | Customer experience rebuilt around AI |
| Cresta | AI operating system for CX | Contact centres focused on loyalty as well as service |
| Decagon | AI concierge agents | Building and tuning agents for every customer |
| Forethought | AI agents for any helpdesk | Resolving issues on top of an existing CX platform |
| Intercom | Human and AI customer service system | AI and human agents in one support system |
| Maven AGI | Conversational agent platform | Customer conversations handled by AI agents |
| Netomi | Enterprise AI customer experience | Larger companies exploring AI-led service |
| Parloa | Voice and chat agent management | Building and testing voice and chat agents |
| Yellow.ai | Multi-model enterprise AI agents | Enterprises wanting agents built on several models |
Customer service agents from A to Z
One line each on who the platform suits, from the vendor's own description.
Crescendo
Best for: Support leaders rebuilding customer experience around AI; the vendor describes an AI-native CX platform, so ask early how human agents fit in.
Cresta
Best for: Contact centre teams that want what the vendor calls an AI operating system for customer experience, aimed at loyalty and revenue as well as service.
Decagon
Best for: Brands that want to build, tune and scale AI agents giving each customer individual attention; the vendor calls it an AI concierge.
Forethought
Best for: Support teams who want AI agents to resolve customer issues automatically on top of the helpdesk they already use, per the vendor.
Intercom
Best for: Teams who want AI and human customer service in one complete system rather than an agent added on; a free trial is named on its site.
Maven AGI
Best for: Customer-facing teams wanting a conversational agent platform; the vendor's pitch is agents that customers are happy to talk to.
Netomi
Best for: Larger companies looking at AI for customer experience; the vendor speaks in broad terms, so ask for a demo on your own tickets.
Parloa
Best for: Enterprise contact centres that need voice as well as chat agents, with tools to build, test and scale them, as the vendor describes it.
Yellow.ai
Best for: Enterprises wanting AI agents that think, act and resolve, built on several large language models, according to the vendor.
Sierra's pitch, and the two tests for any replacement
Sierra's own homepage keeps it short: it helps businesses build better, more human customer experiences with AI. That's a fair goal, but it doesn't tell you how the thing works, so measure every alternative by two questions instead.
First, how is the agent taught your policies? Refund rules, warranty terms, what counts as an exception and who's allowed to grant one. Some platforms read your help centre; others want structured instructions or workflows. Ask to see exactly where a policy lives and what happens when two of them conflict.
Second, how is a conversation handed to a person? The handover is where customers decide whether they trust the whole system. Check what triggers it, whether the human sees the full history, and whether the customer has to repeat themselves. Platforms split by who they're built for and how much you set up yourself, so run the same real conversation through each before you decide.
Agent-first, voice-led or full suite
Agent-first platforms
Forethought, Maven AGI, Crescendo and Netomi focus on AI agents resolving issues, and so does the AI concierge in the list above; my Decagon alternatives page goes wider on that one. Some of these sit on top of the helpdesk you already have; others want to become the centre of your CX.
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Voice and contact centres
Parloa and Cresta speak to contact centres, with voice as well as chat in the picture. If most of your volume still arrives by phone, start here.
Several models or one complete system
Yellow.ai builds its agents on several language models, while Intercom brings AI and human service into one system. The second suits teams that want the AI and the human queue in the same place. My broader list of AI customer service tools covers more options of both kinds.
Advice for support leaders
Start with your hardest tickets, not your easiest. Any agent can answer a password reset. The ones that matter are the angry customer, the edge case in your returns policy and the request that needs a person's judgement. Run a set of those through every shortlisted platform, with your real policies loaded, and watch the handover as closely as the answers. If you record calls or store chat transcripts, check the consent and retention rules where you operate; they vary by country, so confirm with your regulator.
Then involve your best human agents early. They know where customers get stuck, and they'll be the ones picking up every handover.
Plan the handover before launch
A clean handover plan makes or breaks the first month. Agree these points before any customer talks to the new agent.
- Which topics the agent may never answer alone.
- What phrases or signals send a conversation to a person straight away.
- What the human sees when they pick up: history, account details and the agent's notes.
- How quickly a person must respond after a handover, and who covers out of hours.
- How agents and the support team report a wrong answer so it gets fixed.
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Frequently asked questions
What does Sierra do?
Sierra builds AI agents for customer service, with the stated aim of more human customer experiences. Alternatives range from agent-first platforms to voice-led tools and full systems that combine AI and human agents.
How do AI support agents learn company policies?
It varies. Some read your help centre and documents, others use structured instructions or workflows you set up. Ask each vendor to show where a policy lives and how conflicts between policies are handled.
When should an AI agent hand over to a person?
When the customer asks, when the issue is outside agreed topics, when emotions run high or when a decision needs judgement. Set these rules before launch and test them with real conversations.
Can AI agents handle phone support?
Some platforms cover voice as well as chat. If most of your volume comes by phone, test voice conversations specifically, because what works in chat doesn't always work on a call.
Are there rules on recording support conversations?
Yes. Rules on recording calls, storing transcripts and using them to train systems vary by country, so check with your regulator before switching anything on.
Is this list ranked?
No. It's alphabetical in the list and grouped by how each platform approaches customer service.
