PolyAI vs Sierra
A side-by-side comparison of PolyAI and Sierra, drawn from Ignaite's continuously-verified listings.
Compared from listings verified as of
At a glance
| Attribute | PolyAI | Sierra |
|---|---|---|
| Category (differs) | Voice | Support |
| Pricing | PAID | PAID |
| License | Proprietary | Proprietary |
| Deployment | Cloud | Cloud |
| Platforms | Web, API | Web, API |
| Model support (differs) | Self-contained (on-device) | Multi-model |
| Vendor (differs) | PolyAI | Sierra |
| Capabilities (differs) |
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The honest brief
PolyAI
An end-to-end managed contact-center agent on its own Raven model — not a developer toolkit you assemble from telephony, LLM, and TTS parts.
- Handles complex multi-turn calls
- Enterprise compliance built in
- No-code studio plus developer ADK
- 2,000+ live deployments, 45 languages
- Custom enterprise contracts only
- No self-serve or SMB tier
- No public pricing
Sierra
Outcome-based pricing — you pay per successful resolution, not per seat or per conversation.
- Pay per resolved outcome, not flat seats
- Omnichannel: chat, voice, email, SMS, WhatsApp
- Founder pedigree (Bret Taylor, Clay Bavor)
- Heavy Fortune 500 adoption
- Enterprise-only; contracts start six figures
- Plus setup fees in the tens of thousands
- Outcome definitions are negotiated and can drift
- No self-serve or transparent pricing
When to pick which
Both cover Voice agent, AI app builder, and Ticket deflection.
Pick PolyAI if you need Conversation intelligence.
- Conversation intelligence (secondary capability)
Pick Sierra if you need LLM observability.
- LLM observability (secondary capability)
They also differ on:
- Model support
- Self-contained (on-device) · Multi-model