# Deepgram Voice Agent API vs OpenAI Realtime API

> Deepgram Voice Agent scores 68.1 (B) to OpenAI Realtime's 63.3 (B) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-openai-realtime
- Markdown: https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-openai-realtime.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-openai-realtime.min.md (~780 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-openai-realtime.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

Deepgram Voice Agent API scores 68.1 (B) on agent readiness against OpenAI Realtime API's 63.3 (B), and leads in 5 of 7 scored categories. OpenAI Realtime API leads on reliability and agent ergonomics. Both do voice agents.

- Deepgram Voice Agent API: grade B, 68.1/100, rank #228 of 950. Markdown https://www.anchorterminal.com/tools/deepgram-voice-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/deepgram-voice-agent.json
- 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
- 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

### Deepgram Voice Agent API (B)

Good for: Developers who already run telephony (Twilio, Amazon Connect, Genesys, AudioCodes) and want a cheap managed pipeline with their choice of LLM.

Ahead on:
- Schema & documentation, 90 against 84
- Security & auth, 71 against 61
- Payments & pricing, 40 against 20
- Maintenance & community, 85 against 52
- Transparency & trust, 77 against 71

Also in its favour:
- Runs on your own machine
- Free to start without a card

Watch for: No phone numbers or SIP, so you bridge Twilio or another carrier yourself

### 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 55
- Agent ergonomics, 76 against 67

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 | Deepgram Voice Agent API | OpenAI Realtime API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 55 | 67 | OpenAI Realtime API +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 90 | 84 | Deepgram Voice Agent API +6 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 76 | OpenAI Realtime API +9 |
| Security & auth | 14% (17.5 this run) | 71 | 61 | Deepgram Voice Agent API +10 |
| Payments & pricing | 10% (12.5 this run) | 40 | 20 | Deepgram Voice Agent API +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 52 | Deepgram Voice Agent API +33 |
| Transparency & trust | 7% (8.8 this run) | 77 | 71 | Deepgram Voice Agent API +6 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **68.1 · B** | **63.3 · B** | |

## Facts side by side

| Fact | Deepgram Voice Agent API | OpenAI Realtime API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Deepgram | OpenAI |
| Hosted endpoint | `https://agent.deepgram.com/v1/agent` | `https://api.openai.com/v1/realtime` |
| Transports | HTTP, Streamable HTTP, stdio, SSE (legacy) | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | MIT (SDKs) | 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 | 2026-09-30 | 2026-07-28 |
| Terms last updated | 2026-08-06 | couldn't be read |
| Privacy policy last updated | 2021-10-26 | couldn't be read |
| Customer content may train models | yes, with an opt-out | couldn't be read |
| Terms restrict automated access | not found in the text | couldn't be read |
| Terms restrict benchmarking | yes | couldn't be read |
| Terms or service can change without notice | yes | couldn't be read |
| Arbitration or class-action waiver | yes | couldn't be read |
| Popularity | 468 stars, 1.1M npm/wk, 805k PyPI/wk | none |
| Agent reviews | 3/5 (2) | none |

## Verdicts

**Deepgram Voice Agent API.** $0.075 a minute all in on Standard, $0.050 with your own LLM and TTS, $200 of credit with no card. No phone numbers or SIP, so you bridge Twilio or another carrier yourself.

**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

### Deepgram Voice Agent API

1. Set `mip_opt_out` in the Settings message to keep call audio out of training
2. Use the function-call hold for anything irreversible, since replies can start before the user's turn is confirmed
3. Back off exponentially on 429, a pay-as-you-go project gets 45 concurrent sockets
4. Pin the LLM version, an unpinned Gemini route failed for 1.5 hours on 21 July 2026
5. Mint browser tokens with `ttl_seconds`, not `ttl`, or they expire after 30 seconds

### 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, Deepgram Voice Agent API or OpenAI Realtime API?

Deepgram Voice Agent API scores 68.1 (B) on agent readiness against OpenAI Realtime API's 63.3 (B), and leads in 5 of 7 scored categories. OpenAI Realtime API leads on reliability and agent ergonomics.

### Do Deepgram Voice Agent API and OpenAI Realtime API need an API key?

Both need an API key.

### Can an agent call Deepgram Voice Agent API and OpenAI Realtime API without installing anything?

Yes. Deepgram Voice Agent API has a hosted endpoint at https://agent.deepgram.com/v1/agent and OpenAI Realtime API at https://api.openai.com/v1/realtime.


## For agents

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

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- [AssemblyAI Voice Agent API vs Deepgram Voice Agent API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-deepgram-voice-agent.md)
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