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Vapi AI vs OpenAI Realtime API

This comparison was retrieved by database IDs selected from the catalog.

Vapi AI favicon

Vapi AI

Vapi

OpenAI Realtime API favicon

OpenAI Realtime API

OpenAI

Overview
Rating
—
—
Category
Developer Tools
Developer Tools
Subcategory
Voice AI API Platform
Real-Time Voice and Multimodal AI API
Company
Vapi
OpenAI
Status
Active
Active
Launch year
2023
2024
Tags
voice-aiapiphone-agentdeveloper-toolsreal-timeautomation
voice-airealtimeapigpt-4oaudiodeveloper-tools
Pricing
Starting price
FreeBest value
Free
Pricing model
Usage-based
Usage-based
Free plan
Yes
No
Free trial
✕
✕
Pricing notes

Free plan with $10 credits. Pay-as-you-go from $0.05/minute. Volume discounts available. Enterprise custom.

Pay-as-you-go. Audio input $0.06/min, audio output $0.24/min (as of 2025). Text within realtime sessions at standard GPT-4o rates. No free tier.

Capabilities
Best for
AI phone agent developmentAutomated customer service voiceOutbound call automationVoice assistant developmentInteractive voice response (IVR) replacement
Low-latency voice AI assistant developmentNatural conversational AI phone agentsReal-time audio AI processingVoice-powered AI agent developmentEmotional voice AI experiences
Target audience
AI developersVoice application buildersCustomer service automation engineersStartup foundersEnterprise telephony teams
AI developersVoice application buildersStartup foundersEnterprise developersResearch teams
AI type
Audio Processing AI
Conversational AI Agent
Modalities
AudioText
AudioText
Technical
Model provider
OpenAIAnthropicGoogleElevenLabsDeepgram
OpenAI
Model names
GPT-4oClaudeGeminiElevenLabs TTS
GPT-4o
API available
✓
✓
Open source
✕
✕
Deployment
SaaSAPI
SaaSAPI
Platforms
WebAPI
WebAPIWebSocket
Integrations
TwilioVonageElevenLabsDeepgramOpenAIAnthropicAPI
WebRTCVapiTwilioAPI
Team collaboration
✕
✕
Trust & security
Security

Review Vapi's data handling policy. Call audio, transcripts, and user data processed on Vapi's infrastructure.

Review OpenAI's data handling policy. Audio streams processed on OpenAI's infrastructure. Review Enterprise data handling terms for sensitive audio applications.

Privacy notes

Review Vapi's privacy policy. Call audio is processed in real-time on Vapi's infrastructure. Call recordings and transcripts may be stored per configuration. Review implications for call recording consent laws.

Audio data processed on OpenAI's servers. By default, audio is not used for training. Review OpenAI's API data handling policy for sensitive voice applications.

Verdict
Pros
  • Sub-1-second latency voice pipeline enables natural conversational AI phone experience
  • Model-agnostic design allows optimising LLM and TTS provider for specific use case requirements
  • $0.05/minute pay-as-you-go with $10 free credit makes evaluation accessible
  • Concurrent call scaling handles production voice agent workloads without infrastructure management
  • Native audio processing preserves emotional cues and prosody lost in STT-text-TTS pipelines
  • Sub-second latency enables natural conversational AI experiences matching human conversation speed
  • Same technology powering ChatGPT Advanced Voice Mode provides validated quality benchmark
  • Function calling in voice enables voice AI agents that complete tasks rather than only answering questions
Cons
  • Call recording consent laws vary by jurisdiction — review before deploying in regulatory contexts
  • Voice AI user experience is highly sensitive to latency — evaluate in the target deployment environment
  • $0.05/minute costs can scale significantly for high-volume outbound calling programmes
  • $0.24/min audio output pricing accumulates quickly for high-volume voice applications
  • WebSocket architecture requires different implementation approach than standard REST API calls
  • Limited to GPT-4o — no model flexibility for latency vs cost trade-offs

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