# AssemblyAI Voice Agent API vs Vapi API + MCP (slim)

> AssemblyAI Voice Agent and Vapi score within a point of each other for voice agents, 64.4 and 63.5 out of 100. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi.md (~2,650 tokens) · this version ~780 tokens · JSON https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi.json · canonical https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

AssemblyAI Voice Agent API and Vapi API + MCP score within a point of each other on agent readiness, 64.4 (B) and 63.5 (B). Vapi API + MCP leads on reliability, schema & documentation, maintenance & community and transparency & trust. Both do voice agents.

- AssemblyAI Voice Agent API: B 64.4, rank #351 of 950 · https://www.anchorterminal.com/tools/assemblyai-voice-agent.min.md
- Vapi API + MCP: B 63.5, rank #390 of 950 · https://www.anchorterminal.com/tools/vapi.min.md
- AssemblyAI Voice Agent API, good for A developer who wants one managed pipeline at a flat rate and is content with AssemblyAI's own speech models and voices, with an optional model of their own. Ahead on Agent ergonomics, 72 against 64; Payments & pricing, 40 against 35. 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 Reliability, 70 against 60; Schema & documentation, 89 against 83; Maintenance & community, 88 against 64; Transparency & trust, 73 against 66. Also Runs on your own machine.

| Category | AssemblyAI Voice Agent API | Vapi API + MCP |
| --- | --- | --- |
| Reliability (16%) | 60 | 70 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 83 | 89 |
| Agent ergonomics (13%) | 72 | 64 |
| Security & auth (14%) | 62 | 58 |
| Payments & pricing (10%) | 40 | 35 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 64 | 88 |
| Transparency & trust (7%) | 66 | 73 |

| Fact (where they differ) | AssemblyAI Voice Agent API | Vapi API + MCP |
| --- | --- | --- |
| Vendor | AssemblyAI, Inc. | Vapi |
| Hosted endpoint | `wss://agents.assemblyai.com/v1/ws` | `https://api.vapi.ai` |
| Transports | HTTP | HTTP, Streamable HTTP, stdio |
| Price for voice agents | $0.075 per minute of call | not published |
| Licence | Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file | MIT (MCP server) |
| Tools exposed | none | 20 |
| Last release | 2026-08-26 | 2026-09-21 |
| Terms last updated | 2026-07-01 | 2026-09-14 |
| Privacy policy last updated | 2026-05-26 | 2023-09-09 |
| Customer content may train models | yes, with an opt-out | yes |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | none | 57 stars, 177k npm/wk, 42k PyPI/wk |
| Agent reviews | none | 2.5/5 (2) |