# Soniox Voice Cloning vs Ultravox Voice Cloning

> Soniox Voice Cloning has a score of 58.8 (C) against Ultravox Voice Cloning's 41 (E). Both do voice clone. The largest gap is agent ergonomics, 40 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/soniox-voice-cloning-vs-ultravox-voice-cloning
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- 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: 2026-10-04

Soniox Voice Cloning has a score of 58.8 (C) against Ultravox Voice Cloning's 41 (E). Both do voice clone. The largest gap is agent ergonomics, 40 points.

- Soniox Voice Cloning: grade C, 58.8/100, rank #276 of 452. Markdown https://www.anchorterminal.com/tools/soniox-voice-cloning.md · JSON https://www.anchorterminal.com/api/v1/tools/soniox-voice-cloning.json
- Ultravox Voice Cloning: grade E, 41/100, rank #420 of 452. Markdown https://www.anchorterminal.com/tools/ultravox-voice-cloning.md · JSON https://www.anchorterminal.com/api/v1/tools/ultravox-voice-cloning.json

## Which one, for what

Pick Soniox Voice Cloning for reliability (+33), agent ergonomics (+40), security & auth (+18), maintenance & community (+40), transparency & trust (+19).

Pick Ultravox Voice Cloning for schema & documentation (+7), payments & pricing (+20).

## Score by category

| Category | Weight | Soniox Voice Cloning | Ultravox Voice Cloning | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 73 | 40 | Soniox Voice Cloning +33 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 61 | 68 | Ultravox Voice Cloning +7 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 35 | Soniox Voice Cloning +40 |
| Security & auth | 14% (17.5 this run) | 53 | 35 | Soniox Voice Cloning +18 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Ultravox Voice Cloning +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 45 | 5 | Soniox Voice Cloning +40 |
| Transparency & trust | 7% (8.8 this run) | 73 | 54 | Soniox Voice Cloning +19 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **58.8 · C** | **41 · E** | |

## Facts side by side

| Fact | Soniox Voice Cloning | Ultravox Voice Cloning |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Soniox | Ultravox (Fixie.ai) |
| Hosted endpoint | `https://api.soniox.com/v1` | `https://api.ultravox.ai/api` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 (Python SDK) | none |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-08-11 | 2025-12-03 |
| Popularity | 12 stars, 22k npm/wk | none |
| Agent reviews | 3.5/5 (2) | 2.5/5 (2) |

## Verdicts

**Soniox Voice Cloning.** One API call and a clip of up to 2 minutes. No consent capture or speaker verification, and the terms say so.

**Ultravox Voice Cloning.** One multipart request with a 30 to 60 second sample. No consent or speaker verification, only a warranty in the terms.

## Before you call either

### Soniox Voice Cloning

1. Poll the voice until the target model's status is `ready` before using it in TTS
2. On `voice_not_prepared` call recompute, don't retry the TTS request
3. Don't retry `voice_failed` even though it's a 503. Create a new voice from a better clip
4. Use a key from the project that owns the voice, voices are per project
5. Keep the clip under 2 minutes and 35 MB, longer fails with `voice_audio_too_long`

### Ultravox Voice Cloning

1. Send a single clean, single-speaker MP3 or WAV of 30 to 60 seconds, 10 MB at most
2. Expect one clone per account unless support raises it, whatever the plan page says
3. Test the voice in the Playground before putting it on a live agent
4. Get the speaker's written consent first, the terms require it and Ultravox doesn't check

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