Retell AI

Company Overview

Retell AI is a startup offering an API for building advanced voice AI agents that can interact like humans. The company is based in the Bay Area and was founded in 2023. Retell AI is backed by Y Combinator as part of their Winter 2024 batch.

The company’s mission is to push the boundaries of user-friendliness for voice AI to reach mainstream adoption. Retell AI believes voice AI will become the primary interface for accessing products and services, revolutionizing human-machine interactions.

Products Overview

Retell AI’s core product is a conversational voice API that allows developers to build human-like voice AI agents with minimal code. Key features include:

• Response times averaging 800ms, reaching human-level interaction speeds
• Handling of interruptions and smart turn-taking for seamless conversations
• Support for both phone calls and web calls
• Simple agent creation using prompts or custom LLM integration
• Live transcription feature
• Function calling capabilities to access real-time data and perform actions

The API can be used to build AI call agents, AI coaching apps, AI companions, and other voice-based AI applications. Retell AI provides SDKs for Node.js and Python to make integration easier.

Founding Team

The founding team of Retell AI includes:

• Bing Wu - CEO
• Zexia Zhang - CTO
• Todd Li - President
• Weijia Yu - COO
• Evie Wang - CMO

The founders have expertise from companies like Google, TikTok, ByteDance, and Meta.

Problem and Market Fit

Retell AI is addressing the challenge of building voice AI agents that can interact naturally like humans. Key problems they are solving include:

• Reducing development time - Developers often spend hundreds of hours just on the voice conversation experience
• Improving interaction quality - Many current voice AI products have long response latencies, interrupt inappropriately, and handle user interruptions poorly
• Simplifying integration - Retell AI aims to allow developers to create advanced voice agents with minimal code

The company sees a market opportunity as voice becomes an increasingly important interface, with applications across customer service, sales, coaching, companionship and more.

Business Model

Retell AI offers its API on a usage-based pricing model:

• Conversation voice engine API: $0.08-$0.10 per minute depending on voice used
• LLM Agent: $0.02-$0.20 per minute depending on model
• Telephony: $0.01 per minute for Retell’s Twilio integration

The company also offers enterprise pricing for high-volume customers.

Funding and Runway

Retell AI is backed by Y Combinator as part of their Winter 2024 batch. The company has also raised funding from several angel investors, including:

• Jack Altman (Managing Partner of Alt Capital)
• Aaron Levie (CEO of Box)
• Siqi Chen (CEO of Runway)
• Michael Seibel (YC Group Partner)

The total funding amount is not publicly disclosed.

Competitive Landscape

Retell AI is competing in the voice AI and conversational AI space. Some notable competitors include:

• Traditional cloud speech services like Google Cloud Speech-to-Text/Text-to-Speech
• Conversational AI platforms like Dialogflow and Rasa
• Voice AI companies like SoundHound and Nuance
• Large tech companies building voice assistants like Apple, Google, and Amazon

Retell AI aims to differentiate through its focus on human-like interactions, low latency, and developer-friendly API.

Customers

While specific customer names are not disclosed, Retell AI’s website shows logos of companies using their technology, including:

• PwC
• Spare
• Braintrust
• Regal
• JustCall

The company targets developers and businesses looking to build voice AI applications across industries.

Relevant News

• January 2024: Retell AI launched its conversational voice API publicly
• February 2024: Added new TTS options including Deepgram and more voices from ElevenLabs
• March 2024: Introduced multilingual support for German, Spanish, Hindi, Portuguese and Japanese
• April 2024: Released Retell LLM in beta, a framework for building low-latency conversational LLM agents
• May 2024: Added new features including call analysis, backchanneling, and Python custom LLM updates

The company continues to rapidly iterate on its product, regularly releasing new features and improvements.