Vapi AI and Retell AI are both AI calling platforms that offer strikingly similar capabilities when it comes to building voice agents, sharing a common approach of providing programmable, real-time AI phone interactions. Both platforms focus on enabling dynamic, conversational experiences over the phone, with strong support for integrating custom logic and LLMs.
However, they differ in their user focus—Vapi AI leans more towards developers, offering greater flexibility and control through code-heavy interfaces and APIs, while Retell AI emphasizes ease of use with a more intuitive, user-friendly interface that lowers the barrier for non-technical users to build and manage voice agents effectively.
When it comes to voice quality, Vapi and Retell are virtually indistinguishable. Both platforms leverage high-quality voice models like ElevenLabs and other leading providers, resulting in nearly identical speech output in terms of naturalness and clarity. In our experience as an agency, ElevenLabs has been sufficient for all use cases so far, and both platforms support configuration of voice settings such as tonality and speed to fine-tune the experience.
While Vapi does offer a broader selection of voice and AI models compared to Retell, the core quality remains the same—especially since both platforms utilize OpenAI for generating responses. That said, Vapi tends to be quicker to adopt new models, with Retell incorporating them once they're more established. Overall, the voice quality and flexibility between the two are closely matched, with Vapi offering slightly more options for those who need them.
In terms of speed and latency, Vapi and Retell once again offer very similar performance, largely because both platforms are connecting to the same underlying services to produce their output—such as the same speech and AI models.
However, based on our agency's testing, Retell consistently edges out Vapi by a slight margin when it comes to latency. The difference is minimal, but noticeable in real-time interactions where every millisecond counts. For a deeper dive into our testing methodology and results, you can check out our detailed comparison video here:
Pricing between Vapi and Retell differs significantly and could be a deciding factor depending on your use case. On Vapi, the cost of running an agent can range from $0.11 to $0.25 per minute, depending on factors like prompt length, model selection (e.g., GPT-4.1 or 4.1 Mini), and the use of ElevenLabs voices. As you increase prompt complexity and context, pricing scales accordingly.
In contrast, Retell offers a more predictable and cost-effective pricing model, charging a flat rate of $0.08 per minute for the same setup—regardless of prompt size or complexity. This is possible because Retell has averaged out their input costs, which can provide a major advantage for teams with longer, more detailed prompts or high call volumes.
Both Vapi and Retell offer robust integration capabilities, allowing function calls to send and receive data with virtually any external application—typically through automation platforms like Zapier or Make.com. The core functionality is identical across both platforms, enabling seamless data flows during AI calls. Vapi has a slight edge when it comes to ease of setup, offering a more user-friendly UI for configuring these connections, whereas Retell requires writing and managing JSON manually, which can be a bit more technical.
That said, Retell shines with its built-in Cal.com integration for appointment booking, which we've found to be highly effective and flexible—especially for features like round-robin scheduling and multi-member bookings. While Vapi also integrates directly with Google Calendar, some users have reported limitations, such as the inability to create custom event types. Overall, both platforms support powerful automation workflows, with only minor differences in setup experience and built-in calendar tools.
Vapi and Retell are both powerful AI calling platforms that offer remarkably similar capabilities in voice quality, AI integration, and automation workflows. Both utilize leading voice and language models, provide access to tools like ElevenLabs and OpenAI, and support function calls that allow for seamless data flow to external systems.
While Vapi leans more developer-friendly with greater flexibility and a wider selection of models, Retell offers a smoother experience for non-technical users and includes standout features like a built-in Cal.com integration.
Voice quality and latency are nearly identical, though Retell holds a slight edge in response speed based on our testing. Pricing is one of the few areas where they diverge notably—Vapi uses a variable pricing model that scales with complexity, while Retell offers a simpler, flat-rate structure that may appeal to cost-conscious users. Ultimately, the right choice depends on your team’s specific needs, technical comfort level, and budget priorities.
And since both platforms are evolving rapidly, one of the best long-term strategies is to build a good relationship with the teams behind each product—because staying close to their roadmap and support can be just as valuable as any technical feature.
At Inflate AI, we specialize in building custom, premium AI calling systems—both inbound and outbound—that are tailored to your business needs. Whether you’re looking to automate appointment booking, handle customer service, or streamline lead qualification, we design robust and professional solutions that deliver high levels of accuracy and reliability.
We've partnered with businesses across a wide range of industries, including HVAC, plumbing, wineries, airlines, real estate, travel, and more. Our experience allows us to craft intelligent voice systems that not only sound natural but also integrate seamlessly with your existing tools and workflows.
