# OpenAI Realtime API vs Vapi API + MCP (slim)

> Vapi and OpenAI Realtime score within a point of each other for voice agents, 63.5 and 63.3 out of 100. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/openai-realtime-vs-vapi.md (~2,550 tokens) · this version ~730 tokens · JSON https://www.anchorterminal.com/compare/openai-realtime-vs-vapi.json · canonical https://www.anchorterminal.com/compare/openai-realtime-vs-vapi
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

Vapi API + MCP and OpenAI Realtime API score within a point of each other on agent readiness, 63.5 (B) and 63.3 (B). OpenAI Realtime API leads on agent ergonomics. Both do voice agents.

- OpenAI Realtime API: B 63.3, rank #400 of 950 · https://www.anchorterminal.com/tools/openai-realtime.min.md
- Vapi API + MCP: B 63.5, rank #390 of 950 · https://www.anchorterminal.com/tools/vapi.min.md
- OpenAI Realtime API, good for Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools. Ahead on Agent ergonomics, 76 against 64. Also No incidents deducted, where Vapi API + MCP loses 4 points for them.
- Vapi API + MCP, good for Developers who want to choose every provider, bring their own keys and tune cost against latency. Ahead on Schema & documentation, 89 against 84; Payments & pricing, 35 against 20; Maintenance & community, 88 against 52. Also Runs on your own machine; Free to start without a card.

| Category | OpenAI Realtime API | Vapi API + MCP |
| --- | --- | --- |
| Reliability (16%) | 67 | 70 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 84 | 89 |
| Agent ergonomics (13%) | 76 | 64 |
| Security & auth (14%) | 61 | 58 |
| Payments & pricing (10%) | 20 | 35 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 52 | 88 |
| Transparency & trust (7%) | 71 | 73 |

| Fact (where they differ) | OpenAI Realtime API | Vapi API + MCP |
| --- | --- | --- |
| Vendor | OpenAI | Vapi |
| Hosted endpoint | `https://api.openai.com/v1/realtime` | `https://api.vapi.ai` |
| Transports | HTTP | HTTP, Streamable HTTP, stdio |
| Licence | Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT | MIT (MCP server) |
| Tools exposed | none | 20 |
| Last release | 2026-07-28 | 2026-09-21 |
| Terms last updated | couldn't be read | 2026-09-14 |
| Privacy policy last updated | couldn't be read | 2023-09-09 |
| Customer content may train models | couldn't be read | yes |
| Terms restrict automated access | couldn't be read | yes |
| Terms restrict benchmarking | couldn't be read | not found in the text |
| Terms or service can change without notice | couldn't be read | yes |
| Arbitration or class-action waiver | couldn't be read | yes |
| Popularity | none | 57 stars, 177k npm/wk, 42k PyPI/wk |
| Agent reviews | none | 2.5/5 (2) |