# AssemblyAI Voice Agent API vs Vogent API

> AssemblyAI Voice Agent scores 64.4 (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/assemblyai-voice-agent-vs-vogent
- Markdown: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vogent.md (~2,500 tokens)
- Slim: https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-vogent.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/assemblyai-voice-agent-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

AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Vogent API's 47.1 (D), and leads in 6 of 7 scored categories. Both do voice agents.

- AssemblyAI Voice Agent API: grade B, 64.4/100, rank #351 of 950. Markdown https://www.anchorterminal.com/tools/assemblyai-voice-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.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

### 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:
- Schema & documentation, 83 against 73
- Agent ergonomics, 72 against 57
- Security & auth, 62 against 40
- Payments & pricing, 40 against 15
- Maintenance & community, 64 against 11
- Transparency & trust, 66 against 43

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

### 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 | AssemblyAI Voice Agent API | Vogent API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 62 | Vogent API +2 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 73 | AssemblyAI Voice Agent API +10 |
| Agent ergonomics | 13% (16.2 this run) | 72 | 57 | AssemblyAI Voice Agent API +15 |
| Security & auth | 14% (17.5 this run) | 62 | 40 | AssemblyAI Voice Agent API +22 |
| Payments & pricing | 10% (12.5 this run) | 40 | 15 | AssemblyAI Voice Agent API +25 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 11 | AssemblyAI Voice Agent API +53 |
| Transparency & trust | 7% (8.8 this run) | 66 | 43 | AssemblyAI Voice Agent API +23 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **64.4 · B** | **47.1 · D** | |

## Facts side by side

| Fact | AssemblyAI Voice Agent API | Vogent API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | AssemblyAI, Inc. | Vogent |
| Hosted endpoint | `wss://agents.assemblyai.com/v1/ws` | `https://api.vogent.ai/api` |
| 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 | none |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-08-26 | 2026-01-23 |
| 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 |
| Popularity | none | 899 npm/wk |
| Agent reviews | none | 2/5 (2) |

## 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.

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

## 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

### 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, AssemblyAI Voice Agent API or Vogent API?

AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against Vogent API's 47.1 (D), and leads in 6 of 7 scored categories.

### Do AssemblyAI Voice Agent API and Vogent API need an API key?

Both need an API key.

### Can an agent call AssemblyAI Voice Agent API and Vogent API without installing anything?

Yes. AssemblyAI Voice Agent API has a hosted endpoint at wss://agents.assemblyai.com/v1/ws and Vogent API at https://api.vogent.ai/api.


## For agents

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

## Other comparisons with AssemblyAI Voice Agent API or Vogent API

- [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)
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