AI Tool Comparison
Comparing as AI Agent & Orchestration FrameworksRetell AI vs OpenAI API
Retell AI
VS
OpenAI API
Verdict by Category
Detailed Comparison
Feature
Retell AI
OpenAI API
Pricing
FreemiumRetell AI's Pay-as-you-go plan starts at $0 with $10 in free credits, no commitments, and full platform access. AI Voice Agents cost $0.07-$0.31 per minute depending on the LLM and voice provider selected, with a base cost breakdown of $0.055/min for Retell's voice infrastructure, $0.015-$0.040/min for text-to-speech (ElevenLabs is priciest at $0.040/min), and LLM costs ranging from $0.003/min (GPT 5 nano) to $0.16/min (GPT 5.5). AI Chat Agents start at $0.002+ per message. The plan includes 20 free concurrent calls, with additional concurrency at $8/month each; the first 10 knowledge bases are free, then $8/month each; phone numbers cost $2/month and verified numbers have a one-time $10 fee. Add-ons include Knowledge Base (+$0.005/min), Batch Call (+$0.005/dial), Branded Call ID (+$0.10/outbound call), Advanced Denoising and Safety Guardrails (+$0.005/min each), PII Removal (+$0.01/min), and AI Quality Assurance ($0.10/min after 100 free minutes). The Enterprise plan offers custom pricing with dedicated stable servers, custom SSO, role-based access control, custom MSA/DPA/BAA terms, high concurrent call caps, and 24/7 support with a dedicated portal.
PaidThe OpenAI API uses pay-as-you-go, per-token pricing that varies by model. GPT-5.6 Sol, built for complex reasoning and coding, costs $5.00 per 1M input tokens and $30.00 per 1M output tokens with a 1.05M context length. GPT-5.6 Terra, balancing intelligence and cost, costs $2.00 per 1M input tokens and $12.00 per 1M output tokens. GPT-5.6 Luna, designed for cost-sensitive, high-volume workloads, costs $0.20 per 1M input tokens and $1.20 per 1M output tokens. All three share a 1.05M context length and 128K max output tokens. Additional costs apply for fine-tuning, evals, and specialized tools like web search or file search depending on usage. New accounts must add billing details before making live API calls, and there is no free-tier token quota; enterprise organizations can contact sales for custom pricing, dedicated support, and advanced data residency and retention controls.
Categories
AI ChatbotsAI No-Code / Automation ToolsAI Developer APIs & PlatformsAI Audio & Music Tools
AI Developer APIs & PlatformsAI Coding AssistantsLarge Language Models (LLMs)
Summary
Build human-like AI voice agents for phone calls with ~600ms latency
Developer platform for GPT models, AI agents, and real-time voice
Retell AI Pros & Cons
Pros
- Industry-leading ~600ms latency for natural, fluid conversations
- True pay-as-you-go billing with no annual contracts required to start
- Highly configurable flow builder with real-time function calling
- Broad LLM and TTS provider choice, including Claude, GPT, and Gemini models
- SOC 2, HIPAA, and GDPR compliant out of the box
- Simulation testing and detailed call analytics for continuous quality improvement
Cons
- Billing continues during silence and hold time since speech recognition stays active
- Advanced voices like Elevenlabs cost more per minute than platform-native voices
- Enterprise-grade features like SSO and custom BAAs require the custom-priced Enterprise plan
- Costs can add up quickly at scale when combining premium LLMs, TTS, and add-ons like AI QA
- No native mobile app; management happens through the web dashboard
OpenAI API Pros & Cons
Pros
- Access to frontier GPT-5.6 models spanning a full range of intelligence and cost tiers
- Comprehensive platform covering text, agents, voice, and multimodal use cases in one place
- Agents SDK and built-in tools simplify building production-grade autonomous agents
- Strong enterprise security posture, including SOC 2 Type 2 and HIPAA BAAs
- No training on API business data by default, with zero data retention available by request
- Extensive documentation, cookbook examples, and an active developer community
Cons
- Pay-as-you-go token costs can scale quickly for high-volume or long-context applications
- New accounts must add billing details before making API calls, with no ongoing free-tier quota
- Frontier reasoning models like GPT-5.6 Sol carry premium per-token pricing versus smaller models
- Enterprise features like dedicated support and advanced data residency require contacting sales
- Rate limits and model access can vary by usage tier, requiring spend history to unlock higher limits