Retell AI
Free tier#1 AI Voice Agent Platform for Automating Phone Calls
Free tier available·All audiences·Powered by Multiple (OpenAI GPT, Anthropic Claude, Google Gemini, Custom LLM)·API available
Key strengths
Low-latency (~600ms) voice AI orchestrationHigh workflow accuracy (95.7% in independent benchmark)No-code drag-and-drop agent builderEnterprise-grade compliance (HIPAA, SOC2 Type II, GDPR, ISO 27001)Outbound campaign dialer built-inAI Quality Assurance up to 100% of callsOn-premises deployment option
Free tier + paid plans
Self-hostable
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Retell AI — Developer Docs & Integration
Retell AI exposes a REST API for full programmatic control over agent configuration, call initiation, campaign management, and analytics retrieval. Developers can integrate Retell AI into existing stacks or build net-new voice automation pipelines.
Integration surface:
- Telephony: Native integrations with Twilio, Vonage, Telnyx, and SIP trunking for BYOC (Bring Your Own Carrier) setups
- Automation platforms: Make and n8n for workflow orchestration
- CRM: HubSpot and Go High Level for lead and contact management
- Custom LLM support: Connect your own LLM endpoint alongside hosted options (OpenAI GPT, Anthropic Claude, Google Gemini)
Deployment options:
- Cloud-hosted (managed)
- On-premises / self-hosted for organizations with strict data residency or compliance requirements
Compliance certifications available: HIPAA, SOC2 Type II, GDPR, ISO 27001 — relevant for enterprise procurement and security reviews.
Pricing model: Usage-based with no annual contract. $0.07–$0.31/min (Voice Agents); $0.002+/msg (Chat Agents). $10 free credits on signup. Enterprise tier available with custom pricing.