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

> OpenAI Realtime scores 63.3 (B) to Synthflow's 51.1 (D) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.md (~2,600 tokens) · this version ~730 tokens · JSON https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow.json · canonical https://www.anchorterminal.com/compare/openai-realtime-vs-synthflow
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

OpenAI Realtime API scores 63.3 (B) on agent readiness against Synthflow API + MCP's 51.1 (D), and leads in 5 of 7 scored categories. Synthflow API + MCP leads on maintenance & community. Both do voice agents.

- OpenAI Realtime API: B 63.3, rank #400 of 950 · https://www.anchorterminal.com/tools/openai-realtime.min.md
- Synthflow API + MCP: D 51.1, rank #756 of 950 · https://www.anchorterminal.com/tools/synthflow.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 Reliability, 67 against 45; Agent ergonomics, 76 against 45; Security & auth, 61 against 51; Payments & pricing, 20 against 0; Transparency & trust, 71 against 66.
- Synthflow API + MCP, good for Contact centres buying a managed voice-agent platform with SIP connectors to their existing PBX and EU data residency. Ahead on Maintenance & community, 68 against 52.

| Category | OpenAI Realtime API | Synthflow API + MCP |
| --- | --- | --- |
| Reliability (16%) | 67 | 45 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 84 | 87 |
| Agent ergonomics (13%) | 76 | 45 |
| Security & auth (14%) | 61 | 51 |
| Payments & pricing (10%) | 20 | 0 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 52 | 68 |
| Transparency & trust (7%) | 71 | 66 |

| Fact (where they differ) | OpenAI Realtime API | Synthflow API + MCP |
| --- | --- | --- |
| Vendor | OpenAI | Synthflow |
| Hosted endpoint | `https://api.openai.com/v1/realtime` | `https://api.synthflow.ai/v2` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | API key | OAuth or key |
| Pricing | Pay per use | Paid |
| Licence | Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT | none |
| Tools exposed | none | 60 |
| Last release | 2026-07-28 | 2026-10-01 |
| Terms last updated | couldn't be read | 2026-05-13 |
| Privacy policy last updated | couldn't be read | no date given |
| Customer content may train models | couldn't be read | not found in the text |
| Terms restrict automated access | couldn't be read | not found in the text |
| Terms restrict benchmarking | couldn't be read | not found in the text |
| Terms or service can change without notice | couldn't be read | not found in the text |
| Arbitration or class-action waiver | couldn't be read | not found in the text |
| Agent reviews | none | 2/5 (2) |