Retell and Vapi are two of the most-shortlisted platforms for building AI voice agents. They overlap heavily, and either can build a production agent. This page is written by Retell, so read it knowing that, but we have kept every claim to what is documented and observable, said plainly where Vapi is strong, and dated the whole thing. Verify anything load-bearing against both platforms' current docs.
Both platforms sit in the same category: infrastructure for building AI agents that hold real phone conversations. The genuine difference is center of gravity.
You want a platform that carries more of the operational load: agent building and versioning, pre-launch testing, call monitoring and analytics, and compliance posture (SOC 2 Type II, HIPAA support) out of the box. Teams shipping voice agents into real business operations, especially where a non-engineer will help run them, tend to land here.
Your team is engineering-led, wants maximal low-level control over the voice pipeline, and prefers to assemble orchestration, evaluation, and monitoring themselves. Vapi's API-first surface rewards teams who treat the voice agent as a component they fully own in code.
Neither is a wrong answer. The costly mistake is picking the platform whose center of gravity doesn't match how your team actually works.
| Retell | Vapi | |
|---|---|---|
| Positioning | Voice AI agent platform: API plus built-in agent building, testing, and monitoring tooling | Developer-first voice AI API: maximal configurability, assemble-your-own tooling |
| Pricing model | Per minute of conversation; volume tiers. See current pricing page | Per minute of conversation; components (voice, model, telephony) priced per configuration. See current pricing page |
| Telephony | Built-in numbers or bring your own via SIP / Twilio | Built-in numbers or bring your own via SIP / Twilio |
| LLM flexibility | Multiple providers supported, including custom LLM endpoints | Multiple providers supported, including custom LLM endpoints |
| Agent building | Visual agent builder plus API; prompt and flow versioning in-platform | Primarily API and config driven; dashboard available, code is the primary surface |
| Testing and QA | Built-in simulated test conversations before deploy | Testing typically assembled by the team via API |
| Compliance posture | SOC 2 Type II, HIPAA support published | Publishes security and compliance information; verify current certifications against your requirements |
| Best-fit buyer | Product and ops teams shipping agents into business operations | Engineering teams building voice as a fully-owned component |
Sourcing note: in production, every row in this table links to the specific vendor documentation or pricing page it is drawn from, with a capture date. Both platforms ship quickly; treat any comparison older than a quarter as stale, including this one.
This section exists because a comparison that can't name its author's weaknesses isn't worth your time.
Both platforms offer self-serve access, so the strongest evaluation is empirical: build the same narrow agent on both, call it twenty times with your real scenarios, and compare transcripts, latency feel, and how long each iteration took. That test costs an afternoon and beats any comparison table, including this one.
Already on Vapi? Prompt logic, knowledge sources, numbers, and integration endpoints all transfer conceptually. Talk to our team about scoping a migration against your current setup.
Both price per minute of conversation, and effective cost depends on configuration: which voice, model, and telephony you attach, and your volume tier. For most configurations the platforms land in a similar range. Compare current published pricing against your expected call profile rather than headline rates.
Both are developer-friendly. Vapi positions around API-first flexibility and low-level control; Retell pairs its API with more built-in operational tooling. Developers who want to assemble everything themselves may prefer Vapi; teams who want the platform to carry operational load tend to prefer Retell.
Yes. Migration effort depends on how much custom orchestration you built. Retell's team supports migrations and can scope one against your current setup.
Both support multiple LLM providers and custom model endpoints. Check current documentation for supported providers and the latency tradeoffs of custom LLMs.