TL;DR: Retell AI is the most-trusted, fastest-growing voice agent platform for production contact-center use – it pairs roughly 600ms latency and clean turn-taking with a visual flow builder and strong telephony, and it is model-agnostic so you keep control of the LLM. It earns the highest reliability score on our rubric and, with reported traction near $50M ARR, it is the mid-market platform most teams should shortlist. App Score: 8.2/10.
How we scored Retell AI
Weighted against our AI voice agent rubric. Sub-scores out of 10; weight in brackets.
Our independent score, from our own weighted rubric and verified pricing, kept separate from any sponsorship. Our methodology.
| Starting price | $0.07/min voice-infra base (pay-as-you-go) |
| Real all-in | ~$0.13-0.31/min with STT, LLM and telephony |
| Best for | Contact centers and startups shipping production agents |
| Standout | Best-rated platform; low latency at high concurrency |
| Free trial | $10 credits + 20 free concurrent calls |
| Type | Developer-first, model-agnostic |
Key features of Retell AI
- Real-time STT to LLM to TTS pipeline over WebRTC at roughly 600ms end-to-end, with barge-in and clean turn-taking.
- Single-prompt or visual Conversation Flow builder (node-based state machine) with function/tool calling and multi-agent coordination.
- Model-agnostic: GPT, Claude, Gemini or a custom LLM via WebSocket; standard and premium TTS voices.
- Phone numbers built in or BYO carrier via elastic SIP trunking (Twilio, Telnyx, Vonage); inbound and outbound with warm transfer.
- CRM and tool integrations (HubSpot, Salesforce, Zendesk, Zoho) plus a Zapier marketplace and simulation testing before launch.
- High concurrency for call-center volume, with add-ons for verified numbers, branded caller ID and PII removal.
Who Retell AI is best for
Retell suits contact centers, startups and product teams shipping real production phone agents that need reliable low latency at volume. It is developer-leaning but its visual flow builder makes structured call design approachable, and its ratings and traction make it the safest mid-market bet. Solopreneurs on a tight budget may find the component-based pricing fiddly to estimate.
Pros and cons
Pros
- The most-trusted platform on our list, with the strongest user-satisfaction record we found.
- Consistent ~600ms latency with strong interruption handling.
- Model-agnostic with a genuine visual flow builder plus full API and SDKs.
- Strongest independent traction signal (reported ~$40-50M ARR, real named customers).
Cons
- Pricing is component-based, so the headline $0.07/min understates the real ~$0.13-0.31/min all-in.
- Reviewers cite a steep learning curve for smaller teams.
- Non-English voice quality is weaker than English in some third-party tests.
Verdict
Retell AI is the platform most teams should shortlist first: it is the best-rated and fastest-growing option, delivers low latency at production volume, and keeps you model-agnostic. It edges Vapi on proof and ease while trailing slightly on raw flexibility. Budget for the true all-in per-minute rate and a short ramp, and it is hard to go wrong. Compare it head to head in our best AI voice agents guide.
Frequently Asked Questions
Is Retell AI good?
Yes – Retell is our number two pick at 8.2 out of 10 and the highest-rated on our reliability criterion. It delivers roughly 600ms latency, a visual flow builder and strong telephony, and stays model-agnostic.
How much does Retell AI cost?
Retell’s voice-infrastructure base is $0.07/min with no mandatory subscription, but STT, LLM and telephony are billed on top, so realistic all-in pricing is about $0.13-0.31/min depending on the model. New accounts get $10 in credits and 20 free concurrent calls.
Retell AI vs Vapi – which is better?
Both are excellent developer platforms. Retell scores 8.2 to Vapi’s 8.1: it edges ahead on ratings, ease of setup and measured latency, while Vapi wins on raw build flexibility and BYO-model control. Retell is the safer default; Vapi is for teams that want maximum control.
Does Retell AI support outbound calling?
Yes. Retell handles both inbound and outbound, with warm transfer, high concurrency and batch outbound. You can use Retell-provided numbers or bring your own carrier via elastic SIP trunking.
