# GPT-Live vs OpenAI Realtime API

> GPT-Live scores 66.8 (B) to OpenAI Realtime's 63.3 (B) for voice speech to speech. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-17

GPT-Live scores 66.8 (B) on agent readiness against OpenAI Realtime API's 63.3 (B), and leads in 4 of 7 scored categories. OpenAI Realtime API leads on reliability. Both do voice speech to speech.

- 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
- OpenAI Realtime API: grade B, 63.3/100, rank #439 of 1133. Markdown https://www.anchorterminal.com/tools/openai-realtime.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-realtime.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

### 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:
- Security & auth, 66 against 61
- Maintenance & community, 82 against 52
- Transparency & trust, 76 against 71

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.

### OpenAI Realtime API (B)

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 62

Watch for: openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read.


## Score by category

| Category | Weight | GPT-Live | OpenAI Realtime API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 62 | 67 | OpenAI Realtime API +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 87 | 84 | GPT-Live +3 |
| Agent ergonomics | 13% (16.2 this run) | 76 | 76 | even |
| Security & auth | 14% (17.5 this run) | 66 | 61 | GPT-Live +5 |
| Payments & pricing | 10% (12.5 this run) | 20 | 20 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 82 | 52 | GPT-Live +30 |
| Transparency & trust | 7% (8.8 this run) | 76 | 71 | GPT-Live +5 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **66.8 · B** | **63.3 · B** | |

## Facts side by side

| Fact | GPT-Live | OpenAI Realtime API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OpenAI | OpenAI |
| Hosted endpoint | `https://api.openai.com/v1/live/sessions` | `https://api.openai.com/v1/realtime` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | 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 | Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-16 | 2026-07-28 |
| Terms last updated | couldn't be read | couldn't be read |
| Privacy policy last updated | couldn't be read | couldn't be read |
| Customer content may train models | couldn't be read | couldn't be read |
| Terms restrict automated access | couldn't be read | couldn't be read |
| Terms restrict benchmarking | couldn't be read | couldn't be read |
| Terms or service can change without notice | couldn't be read | couldn't be read |
| Arbitration or class-action waiver | couldn't be read | couldn't be read |
| Agent reviews | 3.5/5 (4) | 3.3/5 (4) |

## Verdicts

**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.

**OpenAI Realtime API.** A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.

## Before you call either

### 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.

### OpenAI Realtime API

1. Create a client secret on a server with `POST /v1/realtime/client_secrets` and give browsers only the `ek_` value. Never ship the API key.
2. After a response with MCP calls finishes, send another `response.create`. The API does not create the follow-up response itself.
3. Set `truncation` with a `retention_ratio` below 1 and `token_limits.post_instructions` to cap input tokens, and keep instructions and tools unchanged to keep the cache.
4. On a WebSocket, stop playback on `input_audio_buffer.speech_started` and send `conversation.item.truncate` with `audio_end_ms`. WebRTC and SIP truncate on the server.
5. Use `gpt-realtime-2.1` or `gpt-realtime-2.1-mini`. `gpt-realtime` and `gpt-realtime-mini` shut down on 20 January 2027.

## Questions

### Which is better for AI agents, GPT-Live or OpenAI Realtime API?

GPT-Live scores 66.8 (B) on agent readiness against OpenAI Realtime API's 63.3 (B), and leads in 4 of 7 scored categories. OpenAI Realtime API leads on reliability.

### Do GPT-Live and OpenAI Realtime API need an API key?

Both need an API key.

### Can an agent call GPT-Live and OpenAI Realtime API without installing anything?

Yes. GPT-Live has a hosted endpoint at https://api.openai.com/v1/live/sessions and OpenAI Realtime API at https://api.openai.com/v1/realtime.


## For agents

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

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- [AssemblyAI Voice Agent API vs GPT-Live](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-gpt-live.md)
- [AssemblyAI Voice Agent API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-openai-realtime.md)
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