OpenAI Realtime API vs Vapi

There is no straightforward answer because the two products are priced very differently. Vapi charges a base rate of $0.05/min, with real production costs typically ranging from $0.05 to $0.17/min depending on your LLM and TTS choices, which are passed through at cost. OpenAI Realtime API bundles its LLM and voice into its own pricing without passing those costs through separately. Without aligning on the same voice model and call volume, a direct cheaper-or-more-expensive comparison is not possible.

Vapi is the stronger fit for no-code agency deployments. It offers a built-in no-code agent builder, native outbound campaigns, warm transferwarm transfer - Handing a live call to a human with context passed along, rather than a cold drop. to human, a built-in knowledge base, in-platform number provisioning, and partial white-label and sub-account support. OpenAI Realtime API is API-first with no equivalent no-code tooling, no number provisioning, and no bring-your-own LLM or voice flexibility. Vapi starts at $0.05/min with LLM and TTS costs passed through at cost.

Vapi supports bring-your-own LLMBYO LLM - Bring your own language model - use an OpenAI, Anthropic, or self-hosted endpoint instead of the platform default., so you can swap in any model you prefer. OpenAI Realtime API does not offer this option, locking you into OpenAI's own models. If model flexibility is a priority, Vapi is the stronger choice.

Vapi offers a HIPAAHIPAA BAA - A signed Business Associate Agreement that lets you handle protected health information under US healthcare privacy law. Business Associate Agreement, though it is a paid add-on rather than included by default. No HIPAA information is available for OpenAI Realtime API in this comparison. If HIPAA coverage is required, confirm add-on pricing directly with Vapi before committing.

Vapi allows you to bring your own TTSBYO voice - Bring your own text-to-speech voice provider instead of the platform’s built-in voices. voice provider, giving you control over voice quality and cost. OpenAI Realtime API does not support third-party TTS voices. Buyers who need a specific voice or vendor should factor this difference into their decision.

Vapi's base rate starts at $0.05 per minute, though real production costs range from $0.05 to $0.17 per minute depending on the LLM and TTS services used. LLM and TTS costs are passed through at cost. There is no monthly platform fee, and new accounts receive over 60 minutes of free credit to start.

Vapi requires an annual contract to access its best pricing tier, while OpenAI Realtime API does not. Buyers who want flexible, month-to-month commitments may find OpenAI Realtime API easier to start with at scale.

Vapi includes 10 concurrent calls on the base plan, with each additional concurrent line costing $10 per month. The platform reports a median end-to-end latency of 600 ms. Buyers running high-volume outbound campaigns should factor in extra concurrencyconcurrency - How many phone calls the platform can handle at the same time. fees when budgeting.

Vapi lets you buy and port numbers directly within the platform. OpenAI Realtime API does not support in-platform number provisioning. Both platforms support native SIP trunkingSIP trunking - Direct phone-network connectivity that lets the platform place and receive calls without a separate carrier in the middle., so OpenAI Realtime API users need to manage numbers through a separate telephony provider.

Vapi provides GDPRGDPR/EU residency - Compliance with EU data-protection rules, including keeping data stored in the EU. tooling, EU residency options, and consent and recording compliance tooling. However, Vapi does not currently hold SOC 2 Type II certification, and HIPAA coverage requires a paid add-on. Buyers in regulated industries should evaluate whether these limitations meet their requirements.