# OpenAI Realtime API vs Vogent API

> OpenAI Realtime scores 63.3 (B) to Vogent's 47.1 (D) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/openai-realtime-vs-vogent
- Markdown: https://www.anchorterminal.com/compare/openai-realtime-vs-vogent.md (~2,450 tokens)
- Slim: https://www.anchorterminal.com/compare/openai-realtime-vs-vogent.min.md (~580 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/openai-realtime-vs-vogent.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
- Updated: 2026-10-09

OpenAI Realtime API scores 63.3 (B) on agent readiness against Vogent API's 47.1 (D), and leads in every scored category. Both do voice agents.

- OpenAI Realtime API: grade B, 63.3/100, rank #400 of 950. Markdown https://www.anchorterminal.com/tools/openai-realtime.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-realtime.json
- Vogent API: grade D, 47.1/100, rank #838 of 950. Markdown https://www.anchorterminal.com/tools/vogent.md · JSON https://www.anchorterminal.com/api/v1/tools/vogent.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 91 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md

## Which one, for what

### 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
- Schema & documentation, 84 against 73
- Agent ergonomics, 76 against 57
- Security & auth, 61 against 40
- Payments & pricing, 20 against 15
- Maintenance & community, 52 against 11
- Transparency & trust, 71 against 43

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

### Vogent API (D)

Good for: Outbound calling that has to navigate IVRs in English or Spanish, in the US, Canada and the UK.

Watch for: No public changelog and no release found since January 2026


## Score by category

| Category | Weight | OpenAI Realtime API | Vogent API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 67 | 62 | OpenAI Realtime API +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 84 | 73 | OpenAI Realtime API +11 |
| Agent ergonomics | 13% (16.2 this run) | 76 | 57 | OpenAI Realtime API +19 |
| Security & auth | 14% (17.5 this run) | 61 | 40 | OpenAI Realtime API +21 |
| Payments & pricing | 10% (12.5 this run) | 20 | 15 | OpenAI Realtime API +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 52 | 11 | OpenAI Realtime API +41 |
| Transparency & trust | 7% (8.8 this run) | 71 | 43 | OpenAI Realtime API +28 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **63.3 · B** | **47.1 · D** | |

## Facts side by side

| Fact | OpenAI Realtime API | Vogent API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | OpenAI | Vogent |
| Hosted endpoint | `https://api.openai.com/v1/realtime` | `https://api.vogent.ai/api` |
| 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 Agents SDK for TypeScript and the OpenAPI description are MIT | none |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-07-28 | 2026-01-23 |
| 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 |
| Popularity | none | 899 npm/wk |
| Agent reviews | none | 2/5 (2) |

## Verdicts

**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.

**Vogent API.** IVR detection and navigation models for outbound calls. No public changelog and no release found since January 2026.

## Before you call either

### 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.

### Vogent API

1. Send an `idempotencyKey` on `POST /dials`, a reused key returns 409
2. Create a call with `callAgentId`, plus `toNumber` and `fromNumberId` for phone calls
3. Tell the model when to emit `<|transfer|>`, since transfers fire on that tag
4. Verify webhooks with the HMAC in `X-Elto-Signature`
5. Expect new dials to fail at the workspace's concurrent dial limit until calls end

## Questions

### Which is better for AI agents, OpenAI Realtime API or Vogent API?

OpenAI Realtime API scores 63.3 (B) on agent readiness against Vogent API's 47.1 (D), and leads in every scored category.

### Do OpenAI Realtime API and Vogent API need an API key?

Both need an API key.

### Can an agent call OpenAI Realtime API and Vogent API without installing anything?

Yes. OpenAI Realtime API has a hosted endpoint at https://api.openai.com/v1/realtime and Vogent API at https://api.vogent.ai/api.


## For agents

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

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