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 — Technical Overview
Retell AI is a voice AI orchestration platform purpose-built for automating inbound and outbound phone call workflows at scale. It supports multiple LLM backends — including OpenAI GPT, Anthropic Claude, Google Gemini, and custom LLMs — giving developers flexibility in model selection without being locked into a single provider.
Key architectural highlights:
- ~600ms end-to-end voice latency, enabling natural, real-time conversational experiences
- 95.7% workflow accuracy in independent benchmarking
- REST API for programmatic agent creation, call management, and analytics
- No-code drag-and-drop agent builder alongside full API access, supporting both low-code and code-first workflows
- On-premises / self-hosted deployment option for data-sensitive environments
- Enterprise-grade compliance: HIPAA, SOC2 Type II, GDPR, and ISO 27001 certified
- AI Quality Assurance capable of analyzing up to 100% of call volume automatically
- Built-in outbound campaign dialer for high-volume calling operations
Integrations: Make, n8n, Twilio, Vonage, Telnyx, Go High Level, HubSpot, and SIP trunking.
Pricing: Usage-based at $0.07–$0.31/min for AI Voice Agents; $0.002+/msg for AI Chat Agents. Pay-as-you-go with $10 free credits at signup. Enterprise custom pricing available. No annual contract required.