Production voice agent infrastructure — build inbound, outbound, and IVR-replacement agents that scale.

Production voice agent platform — LLM-native phone agents with low-latency streaming and per-minute pricing.
| Spec | Retell AI | Synthflow |
|---|---|---|
| Agent Rank | 73 / 100 (A) | 77 / 100 (A) |
| Autonomy | Autonomous | Autonomous |
| Pricing | Pay per task · Free tier | Freemium · from $29 |
| Open source | No | No |
| Capabilities | Voice, Tool use, Memory | Voice, Tool use, Memory |
| Integrations | 3 apps | 4 apps |
| Verified | Verified | Verified |
| Released | Mar 2025 | Feb 2025 |
Auto-computed from autonomy, capabilities, integrations, pricing, maturity and editorial verification. Updated every deploy. How is this computed?
Auto-computed from autonomy, capabilities, integrations, pricing, maturity and editorial verification. Updated every deploy. How is this computed?
Pick Synthflow if its specific capabilities (Voice, Tool use) match what you need.
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Pick Retell AI if cost is the main constraint. Pick Synthflow if its specific capabilities (Voice, Tool use) match what you need. Most working teams running both can use Retell AI for primary work and Synthflow for the workflows where its specific strengths matter.
Retell AI starts at Pay per task · Free tier; Synthflow starts at Freemium · from $29. Retell AI is the cheaper entry option. For team deployments the TCO can differ — use the AI Agent Rank TCO calculator for your specific volume.
Both Retell AI and Synthflow are Autonomous agents — neither has a meaningful autonomy advantage over the other. The decision should hinge on capabilities and pricing instead.
Adjacent agents in the same category with overlapping capabilities — worth a side-by-side glance before you commit.
Production voice agent infrastructure — build inbound, outbound, and IVR-replacement agents that scale.

AI voice platform with Conversational Agents — production-grade voice cloning, TTS, and voice agents.
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