# AssemblyAI Voice Agent API vs CueLight

> AssemblyAI Voice Agent scores 64.4 (B) to CueLight's 48.8 (D) for voice pipeline. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-15

AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against CueLight's 48.8 (D), and leads in 6 of 7 scored categories. CueLight leads on payments & pricing. Both do voice pipeline.

- AssemblyAI Voice Agent API: grade B, 64.4/100, rank #378 of 1094. Markdown https://www.anchorterminal.com/tools/assemblyai-voice-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/assemblyai-voice-agent.json
- CueLight: grade D, 48.8/100, rank #873 of 1094. Markdown https://www.anchorterminal.com/tools/cuelight.md · JSON https://www.anchorterminal.com/api/v1/tools/cuelight.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 102 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:
- Reliability, 60 against 29
- Schema & documentation, 83 against 50
- Agent ergonomics, 72 against 61
- Security & auth, 62 against 50
- Maintenance & community, 64 against 46
- Transparency & trust, 66 against 54

Also in its favour:
- A hosted endpoint, with nothing to install

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

### CueLight (D)

Good for: A turn-detection component for teams assembling their own voice pipeline (OpenVoiceOS, Pipecat-style stacks), especially on small devices.

Ahead on:
- Payments & pricing, 60 against 40

Also in its favour:
- No key needed to call it
- Open source

Watch for: English only, and the author does not plan other languages soon


## Score by category

| Category | Weight | AssemblyAI Voice Agent API | CueLight | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 29 | AssemblyAI Voice Agent API +31 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 50 | AssemblyAI Voice Agent API +33 |
| Agent ergonomics | 13% (16.2 this run) | 72 | 61 | AssemblyAI Voice Agent API +11 |
| Security & auth | 14% (17.5 this run) | 62 | 50 | AssemblyAI Voice Agent API +12 |
| Payments & pricing | 10% (12.5 this run) | 40 | 60 | CueLight +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 64 | 46 | AssemblyAI Voice Agent API +18 |
| Transparency & trust | 7% (8.8 this run) | 66 | 54 | AssemblyAI Voice Agent API +12 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **64.4 · B** | **48.8 · D** | |

## Facts side by side

| Fact | AssemblyAI Voice Agent API | CueLight |
| --- | --- | --- |
| Kind | HTTP API | SDK + MCP |
| Vendor | AssemblyAI, Inc. | sshah03 (individual developer, name not stated) |
| Hosted endpoint | `wss://agents.assemblyai.com/v1/ws` | no (local only) |
| Transports | HTTP |  |
| Auth | API key | None |
| Pricing | Pay per use | Free |
| x402 | no | no |
| Licence | Proprietary service under AssemblyAI's Terms of Service. The two starter repositories on GitHub carry no licence file | Apache-2.0 |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-08-26 | 2026-10-14 |
| Terms last updated | 2026-07-01 | no document linked |
| Privacy policy last updated | 2026-05-26 | no document linked |
| Customer content may train models | yes, with an opt-out |  |
| Terms restrict automated access | yes |  |
| Terms restrict benchmarking | yes |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | none | 10 stars |

## 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.

**CueLight.** CueLight gives a voice pipeline a local end-of-turn probability every 20 ms from audio alone, with a 1.9 MB model and Apache-2.0 weights. It is one day old, English only, installs from Git rather than PyPI, has no CI or changelog, and its accuracy figures are the author's own.

## 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

### CueLight

1. Feed 320 float32 samples at 16 kHz mono per `push`. Resample first, or the call raises an AssertionError
2. Spell the preset as `snappy` or `careful`. Any other name silently uses default thresholds
3. Call `clear()` before a new call or session. Pass `reset_on_turn_start=False` if your pipeline already resets per turn
4. Pin weights by downloading them to a local folder and passing that path to `from_pretrained`
5. Don't use it to identify speakers or clone voices. The training data's conditions forbid it

## Questions

### Which is better for AI agents, AssemblyAI Voice Agent API or CueLight?

AssemblyAI Voice Agent API scores 64.4 (B) on agent readiness against CueLight's 48.8 (D), and leads in 6 of 7 scored categories. CueLight leads on payments & pricing.

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

AssemblyAI Voice Agent API has a hosted endpoint at wss://agents.assemblyai.com/v1/ws. No hosted endpoint is listed for CueLight.

### Are AssemblyAI Voice Agent API and CueLight open source?

No open-source release is listed for AssemblyAI Voice Agent API. CueLight is open source (Apache-2.0).


## For agents

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

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- [AssemblyAI Voice Agent API vs Bland AI API + MCP](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-bland-ai.md)
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