Difference Between VAPI AI vs RETELL AI Voice AI Platforms

Kiruthika

Mar 18, 2025 • 4 min read

Selecting the optimal AI voice platform has become a critical strategic decision for organizations aiming to enhance customer engagement and operational efficiency in an increasingly competitive market. Two prominent contenders in this space are Vapi AI and Retell AI, each offering unique features tailored to diverse business needs. This comprehensive analysis delves into the strengths and weaknesses of both platforms, providing a detailed comparison to assist in making an informed decision.

What is Vapi AI

Vapi AI is a developer-centric platform designed to empower businesses with customizable tools for building advanced voice AI agents. It caters to enterprises seeking deep customization and flexibility in their voice applications.

PROS	CONS
Enhanced User Experience	Complex Pricing Structure
Advanced Language Processing	Limited Free Concurrency
Strong Developer Support	Restricted Telephony Integration
Robust Customization Options	Lower Uptime Guarantee

What is Retell AI

Retell AI is a platform designed to enhance phone call interactions through advanced AI capabilities, providing features like live transcription and tool calling. It ensures compliance with industry standards by being HIPAA compliant, with SOC 2 Type II compliance in progress.

PROS	CONS
User-Friendly Interface	Limited Customization for Developers
High reliability	Potential Latency Issues
Flexible Pricing Model	Limited Voice Cloning Capabilities
Comprehensive Feature Set	Limited number of agents that can be deployed

Feature Comparison between Vapi AI and Retell AI

Now, we’ll explore the key differences between the basic features of Vapi AI and Retell AI, comparing their capabilities, performance, and suitability for various use cases.

Feature	Vapi AI	Retell AI	Notes
Agent Builder	Single Prompt & Agent Blocks	Single Prompt & Multi Prompt	Retell's multi-prompt system offers more flexibility in conversation design
Custom LLM Support	Yes - Multiple model support	Yes - Multiple model support	Both platforms allow integration with various LLM providers
Multilingual Support	35+ languages	19 languages	Vapi offers broader language coverage
Voice Quality	High-quality TTS	High-quality TTS	Retell offers additional audio customization
Latency	Sub-second latency	Sub-second latency	Both platforms offer similar performance
Uptime SLA	99.94%	99.99%	Retell offers slightly better reliability
Concurrent Calls	10 free concurrent calls	20 free concurrent calls	Retell provides better free tier capacity
Response Time	Real-time	Real-time	Both platforms offer quick response times
Custom Telephony	Limited to Twilio and Vonage	Supports SIP trunking to any telephony	Retell offers more flexible telephony options
Webhook Support	Yes	Yes	Both support real-time event notifications
Post-call Analysis	Yes	Yes	Both offer call analysis capabilities
Real-time Monitoring	Yes	Yes	Both provide live monitoring features
Call Recording	Available with transcription	Available with transcription	Both support call recording
Compliance Certifications	HIPAA, GDPR & SOC 2 (HIPAA: $1,000/month additional)	HIPAA, GDPR, SOC 2 Type 1 & Type 2 (All included)	Retell offers more comprehensive compliance coverage
Webcall Support	Yes	Yes	Both support web-based calling
Knowledge Base	Supported	Supported	Both offer knowledge base integration

Why Choose One Over the Other?

When deciding between Vapi AI and Retell AI, consider the following factors:

Customization Needs: If your business requires deep customization and has the technical expertise to manage complex configurations, Vapi AI's robust customization options and strong developer support may be advantageous.
User-Friendly Experience: For businesses seeking an intuitive interface with comprehensive features and high reliability, Retell AI offers a user-friendly platform with a wide range of functionalities and a higher uptime guarantee.

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Plans and Pricing of Vapi AI and Retell AI

Plan	Vapi AI	Retell AI
Base Rate	$0.05 per minute fixed platform fee	$0.07–$0.31 per minute, depending on selected features
Additional Costs	Extra charges for long prompts; $2.00/month per phone number; Slack support: $5,000/month; HIPAA compliance: $1,000 month	Conversation voice engine API, LLM Agent, Telephony, Knowledge

Which AI is Best For You?

When choosing between Vapi AI and Retell AI, it's essential to align the platform's strengths with your business requirements:

Vapi AI is ideal for organizations seeking deep customization and possessing the technical expertise to manage complex configurations. Its robust developer support and extensive language processing capabilities make it suitable for enterprises with specific AI needs.

However, businesses should be mindful of its complex pricing structure and additional costs for compliance and support.

Retell AI offers a user-friendly interface with a comprehensive feature set, including live transcription, customizable call parameters, and tool calling. Its flexible pricing model and higher uptime guarantee make it a reliable choice for businesses aiming for quick deployment and high reliability.

While it may have limited deep customization options, it provides sufficient flexibility for most business applications.

What Customers Think About Vapi AI and Retell AI

Customer feedback provides valuable insights into the real-world performance of these platforms:

Vapi AI

"Amazing System that they are building. I had issues on a Saturday night, and received a phone call from one of the technicians Sahil and he helped me through my issue. What dedication. I saw some of the other reviews, and they seem to be related to billings, and stuff that could easily be spoken about. I just wanted to give a shout-out to this guy for his passion and dedication to the project." - Robert Peter

Retell AI

Users appreciate Retell AI's efficiency and natural interactions. One reviewer stated, "We’ve been using Retell to build these voice agents for our customer service, for over a year. It’s so natural, people don’t even realize it’s not a human half the time."
Another user highlighted the platform's cost-effectiveness, noting, "Retell AI has no platform fees, meaning you only pay for what matters: the API cost."

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In conclusion, both Vapi AI and Retell AI offer valuable features for enhancing voice interactions. Your choice should depend on your organization's specific needs, technical capabilities, and budget considerations. For businesses requiring deep customization and possessing technical expertise, Vapi AI may be the preferred choice.

Conversely, for those seeking a user-friendly platform with comprehensive features and flexible pricing, Retell AI stands out as a compelling option.