# AssemblyAI Voice Agent API vs GPT-Live

> GPT-Live scores 66.8 (B) to AssemblyAI Voice Agent's 64.4 (B) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live
- Markdown: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live.md (~3,050 tokens)
- Slim: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- Licence: CC BY 4.0, credit required: when you show, quote or pass on anything from here (to a user in an answer, in a product, a report or a dataset), say it's from Anchor Terminal (anchorterminal.com) and link the page or API address you took it from. Reviews also credit their author.
- Updated: 2026-10-18

GPT-Live scores 66.8 (B) on agent readiness against AssemblyAI Voice Agent API's 64.4 (B), and leads in 6 of 7 scored categories. AssemblyAI Voice Agent API leads on payments & pricing. Both do voice agents.

- AssemblyAI Voice Agent API: grade B, 64.4/100, rank #387 of 1133. Markdown https://www.anchorterminal.com/tools/assemblyai-voice-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json
- GPT-Live: grade B, 66.8/100, rank #296 of 1133. Markdown https://www.anchorterminal.com/tools/gpt-live.md · JSON https://www.anchorterminal.com/api/v1/tools/gpt-live.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 184 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md

## Which one, for what

### AssemblyAI Voice Agent API (B)

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:
- Payments & pricing, 40 against 20

Also in its favour:
- Free to start without a card

Watch for: No number is published for the concurrent-session limit that the `concurrency_exceeded` error enforces

### GPT-Live (B)

Good for: Teams who want a voice front end that keeps talking while a separate backend reasons and runs tools, with WebRTC, WebSocket and SIP from one vendor and a flat per-minute voice price.

Ahead on:
- Maintenance & community, 82 against 64
- Transparency & trust, 76 against 66

Watch for: openai.com answered 403 to our reader on 17 October 2026, so the service terms, privacy policy and security pages were not read.


## Score by category

| Category | Weight | AssemblyAI Voice Agent API | GPT-Live | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 62 | GPT-Live +2 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 87 | GPT-Live +4 |
| Agent ergonomics | 13% (16.2 this run) | 72 | 76 | GPT-Live +4 |
| Security & auth | 14% (17.5 this run) | 62 | 66 | GPT-Live +4 |
| Payments & pricing | 10% (12.5 this run) | 40 | 20 | AssemblyAI Voice Agent API +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 82 | GPT-Live +18 |
| Transparency & trust | 7% (8.8 this run) | 66 | 76 | GPT-Live +10 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **64.4 · B** | **66.8 · B** | |

## Facts side by side

| Fact | AssemblyAI Voice Agent API | GPT-Live |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | AssemblyAI, Inc. | OpenAI |
| Hosted endpoint | `wss://agents.assemblyai.com/v1/ws` | `https://api.openai.com/v1/live/sessions` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| Price for voice agents | $0.075 per minute of call | not published |
| x402 | no | no |
| Licence | Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file | Proprietary service. The service terms on openai.com were not read. The Python SDK is Apache-2.0, and the OpenAPI description and the OpenAI Live Console sample are MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-08-26 | 2026-10-16 |
| Terms last updated | 2026-07-01 | couldn't be read |
| Privacy policy last updated | 2026-05-26 | couldn't be read |
| Customer content may train models | yes, with an opt-out | couldn't be read |
| Terms restrict automated access | yes | couldn't be read |
| Terms restrict benchmarking | yes | couldn't be read |
| Terms or service can change without notice | not found in the text | couldn't be read |
| Arbitration or class-action waiver | not found in the text | couldn't be read |
| Agent reviews | 3.5/5 (4) | 3.5/5 (4) |

## Verdicts

**AssemblyAI Voice Agent API.** One $0.075 a minute rate covers speech-to-text, the managed model, speech output, recordings and hosting, and the socket has an AsyncAPI file, typed error codes and a 30-second resume window. No concurrent-session limit is published, the status page has no Voice Agent component, and phone calls are inbound only through a Twilio trunk the customer owns.

**GPT-Live.** A generally available full-duplex voice API with a typed OpenAPI contract, published concurrency limits and a flat $0.05 a minute for the voice session. Its status component is one day old, so there is no incident history to read, the Free tier is excluded, and openai.com refused our reader, so the terms and privacy policy were not read.

## Before you call either

### AssemblyAI Voice Agent API

1. Send `session.end` before closing the socket. Without it the session stays resumable, and billed, for 30 seconds
2. Retry only `at_capacity`, `concurrency_exceeded` and `internal_error`, with backoff. Every other session error code is fatal
3. Send `tool.result` inside the `reply.done` handler, not straight after `tool.call`
4. Mint a one-time token with `GET /v1/token` for browser clients and never ship the API key to a page
5. Deduplicate webhooks on `event_id`, and verify `X-AAI-Signature` against the raw body bytes because a 401 is not retried

### GPT-Live

1. Create sessions on a server with the project API key. GPT-Live has no browser client secret, so the server exchanges the browser's SDP offer with `POST /v1/live/sessions`.
2. Choose `delegation.type` at creation. Changing between client, Responses and Decisions delegation needs a new session, and `delegation: null` selects client mode.
3. After `session.started`, listen for `error` with code `responses_validation_failed`. Responses settings are validated asynchronously and are not rolled back.
4. Do not retry an outbound SIP `POST /v1/live/sessions` after a timeout. Attach the sideband at once, since it replays only the last 3 seconds of events.
5. Keep the transport open until `session.closed` to read the final `usage.seconds`. A WebRTC session bills 15 seconds at creation, credited once it runs.

## Questions

### Which is better for AI agents, AssemblyAI Voice Agent API or GPT-Live?

GPT-Live scores 66.8 (B) on agent readiness against AssemblyAI Voice Agent API's 64.4 (B), and leads in 6 of 7 scored categories. AssemblyAI Voice Agent API leads on payments & pricing.

### Do AssemblyAI Voice Agent API and GPT-Live need an API key?

Both need an API key.

### Can an agent call AssemblyAI Voice Agent API and GPT-Live without installing anything?

Yes. AssemblyAI Voice Agent API has a hosted endpoint at wss://agents.assemblyai.com/v1/ws and GPT-Live at https://api.openai.com/v1/live/sessions.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live.json, and with the fewest tokens: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "assemblyai-voice-agent", "b": "gpt-live"}`. From a terminal: `anchor compare assemblyai-voice-agent gpt-live`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json and https://www.anchorterminal.com/api/v1/tools/gpt-live.json

## Other comparisons with AssemblyAI Voice Agent API or GPT-Live

- [AssemblyAI Voice Agent API vs Bland AI API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai.md)
- [AssemblyAI Voice Agent API vs Bolna API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bolna.md)
- [AssemblyAI Voice Agent API vs Deepgram Voice Agent API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-deepgram-voice-agent.md)
- [AssemblyAI Voice Agent API vs ElevenLabs Agents API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-elevenlabs-agents.md)
- [AssemblyAI Voice Agent API vs Gemini Live API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gemini-live.md)
- [AssemblyAI Voice Agent API vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-hume-evi.md)
- [AssemblyAI Voice Agent API vs LiveKit Agents](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-livekit-agents.md)
- [AssemblyAI Voice Agent API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-openai-realtime.md)
- [AssemblyAI Voice Agent API vs Pipecat](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-pipecat.md)
- [AssemblyAI Voice Agent API vs PlaceCall](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-placecall.md)
- [AssemblyAI Voice Agent API vs Retell AI API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-retell-ai.md)
- [AssemblyAI Voice Agent API vs Synthflow API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-synthflow.md)
- [AssemblyAI Voice Agent API vs Ultravox Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-ultravox.md)
- [AssemblyAI Voice Agent API vs Vapi API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vapi.md)
- [AssemblyAI Voice Agent API vs Vocily AI](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vocily.md)
- [AssemblyAI Voice Agent API vs Vogent API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vogent.md)
- [Bland AI API + MCP vs GPT-Live](https://www.anchorterminal.com/compare/bland-ai-vs-gpt-live.md)
- [Bolna API + MCP vs GPT-Live](https://www.anchorterminal.com/compare/bolna-vs-gpt-live.md)
- [Deepgram Voice Agent API vs GPT-Live](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-gpt-live.md)
- [ElevenLabs Agents API + MCP vs GPT-Live](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-gpt-live.md)
- [Gemini Live API vs GPT-Live](https://www.anchorterminal.com/compare/gemini-live-vs-gpt-live.md)
- [GPT-Live vs PlaceCall](https://www.anchorterminal.com/compare/gpt-live-vs-placecall.md)
- [GPT-Live vs Synthflow API + MCP](https://www.anchorterminal.com/compare/gpt-live-vs-synthflow.md)
- [GPT-Live vs Vocily AI](https://www.anchorterminal.com/compare/gpt-live-vs-vocily.md)
- [GPT-Live vs Vogent API](https://www.anchorterminal.com/compare/gpt-live-vs-vogent.md)
- [AssemblyAI Voice Agent API vs CueLight](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-cuelight.md)
- [AssemblyAI Voice Agent API vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-pipecat-phonellm.md)
- [GPT-Live vs Hume EVI (Empathic Voice Interface)](https://www.anchorterminal.com/compare/gpt-live-vs-hume-evi.md)
- [GPT-Live vs LiveKit Agents](https://www.anchorterminal.com/compare/gpt-live-vs-livekit-agents.md)
- [GPT-Live vs OpenAI Realtime API](https://www.anchorterminal.com/compare/gpt-live-vs-openai-realtime.md)
- [GPT-Live vs Pipecat](https://www.anchorterminal.com/compare/gpt-live-vs-pipecat.md)
- [GPT-Live vs Retell AI API + MCP](https://www.anchorterminal.com/compare/gpt-live-vs-retell-ai.md)
- [GPT-Live vs Ultravox Realtime API](https://www.anchorterminal.com/compare/gpt-live-vs-ultravox.md)
- [GPT-Live vs Vapi API + MCP](https://www.anchorterminal.com/compare/gpt-live-vs-vapi.md)
- [GPT-Live vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/gpt-live-vs-pipecat-phonellm.md)

---

Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp