How to Choose Between Vapi and Retell AI in 2026

Vapi and Retell AI are the two most popular managed platforms for building voice AI agents. Both handle the hard parts — telephony, real-time audio processing, turn detection, and LLM orchestration — so you can focus on building the actual voice experience. But they make different trade-offs. Here’s how to decide.

What do Vapi and Retell actually do?

Both platforms sit between a phone call and an LLM. When someone calls a number, the platform:

1. Receives the audio stream
2. Runs speech-to-text (STT) to transcribe what the caller says
3. Sends the transcript to an LLM with your system prompt
4. Runs text-to-speech (TTS) to convert the LLM’s response to audio
5. Plays that audio back to the caller

They also handle: interrupt detection (when the caller talks over the AI), end-of-turn detection (when to stop listening and respond), call recording, transcripts, webhooks, and phone number management.

The difference is in how they do each of these things, and how much control they give you.

Pricing comparison

Both platforms use per-minute pricing, but the structure differs.

Vapi pricing (2026):

• Base: $0.05/minute platform fee
• Plus your own STT/LLM/TTS API costs (BYOK — bring your own keys)
• Total with typical providers: $0.23–0.35/minute
• No minimum commitment on the base plan

Retell AI pricing (2026):

• Bundled pricing: $0.21–0.30/minute all-in (STT + LLM + TTS + platform)
• Also offers BYOK at lower base rates
• Volume discounts available at 50K+ minutes/month

Which is cheaper? At low volume (<10,000 minutes/month), Retell’s bundled pricing is often simpler and slightly cheaper all-in. At higher volume with BYOK, Vapi’s lower platform fee can win if you negotiate good rates with providers directly.

Neither is dramatically cheaper than the other. Cost is rarely the deciding factor.

Latency comparison

Latency — the time between the caller finishing speaking and the AI starting to respond — is critical for voice AI. Humans start to feel uncomfortable above ~1.5 seconds.

Vapi: Configurable latency based on STT/LLM/TTS choices. With Deepgram STT, Claude Haiku or GPT-4o-mini, and ElevenLabs or Cartesia, typical latency is 600–900ms. With local STT and smaller models, can go lower.

Retell: Optimised for low latency out of the box. Their bundled pipeline typically achieves 500–800ms. Retell has invested heavily in their own turn detection algorithms, which can make conversations feel more natural.

Verdict: Retell has a slight edge on latency consistency — their bundled pipeline is tuned together. Vapi gives you more levers to pull but requires more tuning to achieve the same results.

LLM support

Vapi: Supports any LLM via custom LLM endpoint. You can use OpenAI, Anthropic, Google, Groq, Together AI, or any model you self-host. This is Vapi’s biggest differentiator: complete flexibility on the intelligence layer.

Retell: Supports OpenAI GPT models, Claude models, and a growing list of third-party models. Less flexible than Vapi for cutting-edge or custom models, but covers 90%+ of use cases.

Verdict: Vapi wins on LLM flexibility. If you want to use a fine-tuned model, a specific provider for cost reasons, or switch models frequently, Vapi’s approach is easier.

Voice quality and customisation

Vapi: Integrates with ElevenLabs, Cartesia, Deepgram TTS, OpenAI TTS, and others. You choose and configure the TTS provider. Voice cloning via ElevenLabs is straightforward.

Retell: Has built strong partnerships with ElevenLabs and offers its own voice selection. The out-of-the-box voices are high quality. Custom voice cloning is available.

Verdict: Comparable. Both support the same underlying TTS providers. Vapi gives slightly more configurability; Retell is slightly more opinionated.

Developer experience

Vapi: REST API, server-side SDK (Node.js, Python), client-side SDKs (web, iOS, Android, React Native). The API is verbose and highly configurable, which is powerful but has a steeper learning curve. Documentation is comprehensive but dense.

Retell: REST API, Python and Node.js SDKs. The API is more opinionated — fewer configuration options, but cleaner defaults. Getting a basic agent live is faster. Dashboard is more polished.

Verdict: Retell is faster to get started with. Vapi rewards developers who need granular control.

Enterprise and compliance features

Vapi:

• SOC 2 Type II in progress (as of 2026)
• HIPAA BAA available on Enterprise plan
• Custom telephony (SIP trunks)
• White-labelling
• On-premises deployment available on Enterprise