# Resemble AI Voice Cloning API vs Ultravox Voice Cloning

> Resemble AI Voice Cloning API has a score of 54.3 (C) against Ultravox Voice Cloning's 41 (E). Both do voice clone. The largest gap is agent ergonomics, 31 points. Category scores, facts, verdicts and agent notes side by side.

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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

Resemble AI Voice Cloning API has a score of 54.3 (C) against Ultravox Voice Cloning's 41 (E). Both do voice clone. The largest gap is agent ergonomics, 31 points.

- Resemble AI Voice Cloning API: grade C, 54.3/100, rank #325 of 452. Markdown https://www.anchorterminal.com/tools/resemble-ai-voice-cloning.md · JSON https://www.anchorterminal.com/api/v1/tools/resemble-ai-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 Resemble AI Voice Cloning API for reliability (+25), schema & documentation (+13), agent ergonomics (+31), security & auth (+19), maintenance & community (+25), transparency & trust (+24).

Pick Ultravox Voice Cloning for payments & pricing (+20).

## Score by category

| Category | Weight | Resemble AI Voice Cloning API | Ultravox Voice Cloning | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 65 | 40 | Resemble AI Voice Cloning API +25 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 81 | 68 | Resemble AI Voice Cloning API +13 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 35 | Resemble AI Voice Cloning API +31 |
| Security & auth | 14% (17.5 this run) | 54 | 35 | Resemble AI Voice Cloning API +19 |
| 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) | 30 | 5 | Resemble AI Voice Cloning API +25 |
| Transparency & trust | 7% (8.8 this run) | 78 | 54 | Resemble AI Voice Cloning API +24 |
| Negative events | ≤15 | -4 | 0 | |
| **Total** | | **54.3 · C** | **41 · E** | |

## Facts side by side

| Fact | Resemble AI Voice Cloning API | Ultravox Voice Cloning |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Resemble AI | Ultravox (Fixie.ai) |
| Hosted endpoint | `https://app.resemble.ai/api/v2` | `https://api.ultravox.ai/api` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Paid | Freemium |
| x402 | no | no |
| Licence | none | 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 | 2026-06-30 | 2025-12-03 |
| Popularity | 15 stars, 8.1k npm/wk | none |
| Agent reviews | 2.5/5 (2) | 2.5/5 (2) |

## Verdicts

**Resemble AI Voice Cloning API.** Rapid clones from 10 seconds of audio, ready in under a minute. Cloning API only on Business ($1,000 a month) and Enterprise.

**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

### Resemble AI Voice Cloning API

1. Create the voice, upload recordings or pass `dataset_url`, then call `/build`. Nothing trains until you do
2. Set `callback_uri` rather than polling for `status` to reach `finished`
3. Expect a rapid clone. Since 2026-06-30 API-created voices default to rapid, and create-voice has no field to pick another type
4. Upgrade any voice on a pre-Ultra model before synthesis, since those voices can no longer generate audio
5. Check `success` in every response body, log the request ID, and stay under 40 requests a second per token with your own backoff

### 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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