AI Tools

Retell API: Building Conversational Voice AI

When you’re looking to elevate your product’s user experience with voice interaction, diving into the world of conversational AI can seem daunting. That’s where Retell API comes into play, simplifying the integration of human-like conversational voice AI into your applications. This tool is designed to bridge the gap between the technical complexities of voice AI development and the seamless user experience you aim to provide.


Retell API is a comprehensive solution for developers looking to integrate advanced voice AI into their products without the hassle of piecing together various technologies. It streamlines the process of creating voice agents that can handle natural, human-like conversations with low latency. By offering an easy integration process and support for custom Large Language Models (LLMs), Retell ensures that developers can provide users with interactions that feel real and engaging.

Features & Benefits

  • Easy Integration into Your Product: Retell simplifies the process of adding voice AI capabilities to your application, supporting custom LLM integration for personalized experiences.
  • Ultra-Realistic Voices with Emotions: The API offers voices that not only sound human-like but can also convey emotions, making interactions more engaging.
  • Interruption Handling and Seamless Exchange: With intelligent interruption handling, the system ensures conversations flow smoothly, mimicking natural human dialogues.
  • Low Latency: Approximately 800ms latency means that conversations happen in real-time, without awkward pauses or delays.

Retell Platforms

  • Web app

Retell Tasks

  • Plug in your custom LLM
  • Create voice agents customized for different scenarios
  • Integrate voice experiences to phone/web through WebSocket

Retell Integrations

  • n/a

Real-world applications

Retell API can be a game-changer across various industries where customer interaction is key. In customer service, it can provide 24/7 support without the need for human operators, handling inquiries with a natural flow. E-commerce platforms can use it to assist customers in making purchase decisions through conversational AI. In healthcare, it could facilitate patient interactions, booking appointments, or providing health advice. Education platforms can offer interactive learning experiences, while entertainment services can create engaging voice-controlled games. Financial services can benefit from voice AI for services like banking inquiries and transaction assistance. For tech companies, it simplifies the process of adding voice capabilities to apps, enhancing user engagement. The hospitality industry can use it for bookings and customer service, and transportation services can offer voice-activated ticket bookings and information. Lastly, it’s beneficial for public services, providing an accessible interface for information retrieval and services.

Who is Retell API for

  • Developers
  • Product Managers
  • Tech Entrepreneurs
  • Customer Service Managers
  • Innovators in Education and Healthcare

Pricing & Discount

PlanCost Per MinuteAdditional Costs
API suite with open AI TTS$0.10/minPhone number: $2/month
API suite with 11 labs TTS$0.17/minPhone number: $2/month

Retell API Free version

Not available


  • Customization requires technical expertise, potentially making it less accessible to those without a development background.
  • The emotional range of the voices, while advanced, might still fall short of replicating the full nuance of human emotion.


Users may have concerns about data privacy and security, especially in sensitive applications like healthcare. The technical barrier to entry, including the need for custom LLM integration, might also pose challenges. Pricing could be a concern for small businesses or startups with high usage needs.

Potential Future Developments

Future enhancements could include broader language support, more nuanced emotional expressions in voices, and simpler integration processes for non-developers. Improvements in AI understanding and context awareness could also enhance the user experience.

Try integrating Retell API into your product today to enhance your user experience with seamless voice interactions.

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