# Fish Audio TTS API vs Resemble AI Text-to-Speech API

> Fish Audio TTS API scores 60.7 (C) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 4 of 7 scored categories. Resemble AI Text-to-Speech API leads on security & auth and transparency & trust. Both do speech tts. Category scores, facts, verdicts…

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- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

Fish Audio TTS API scores 60.7 (C) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 4 of 7 scored categories. Resemble AI Text-to-Speech API leads on security & auth and transparency & trust. Both do speech tts.

- Fish Audio TTS API: grade C, 60.7/100, rank #453 of 842. Markdown https://www.anchorterminal.com/tools/fish-audio-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/fish-audio-tts.json
- Resemble AI Text-to-Speech API: grade D, 50.3/100, rank #688 of 842. Markdown https://www.anchorterminal.com/tools/resemble-ai-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/resemble-ai-tts.json

## Which one, for what

### Fish Audio TTS API (C)

Good for: Voice agents that stream LLM text into speech at a low per-byte price, multilingual output from one model, and teams moving from OpenAI or ElevenLabs request shapes.

Ahead on:
- Schema & documentation, 84 against 75
- Agent ergonomics, 67 against 46
- Payments & pricing, 30 against 15
- Maintenance & community, 69 against 31

Also in its favour:
- No incidents deducted, where Resemble AI Text-to-Speech API loses 3 points for them

Watch for: The terms allow Usage Data and Content to train models, with no opt-out found

### Resemble AI Text-to-Speech API (D)

Good for: Operators who already use Resemble for detection or watermarking and want one vendor for both.

Ahead on:
- Security & auth, 48 against 35
- Transparency & trust, 65 against 60

Also in its favour:
- Free to start without a card

Watch for: Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published


## Score by category

| Category | Weight | Fish Audio TTS API | Resemble AI Text-to-Speech API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 75 | 75 | even |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 84 | 75 | Fish Audio TTS API +9 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 46 | Fish Audio TTS API +21 |
| Security & auth | 14% (17.5 this run) | 35 | 48 | Resemble AI Text-to-Speech API +13 |
| Payments & pricing | 10% (12.5 this run) | 30 | 15 | Fish Audio TTS API +15 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 69 | 31 | Fish Audio TTS API +38 |
| Transparency & trust | 7% (8.8 this run) | 60 | 65 | Resemble AI Text-to-Speech API +5 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **60.7 · C** | **50.3 · D** | |

## Facts side by side

| Fact | Fish Audio TTS API | Resemble AI Text-to-Speech API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Fish Audio | Resemble AI |
| Hosted endpoint | `https://api.fish.audio` | `https://app.resemble.ai/api/v2` |
| Transports | HTTP, Streamable HTTP | HTTP |
| Auth | OAuth or key | API key |
| Pricing | Pay per use | Pay per use |
| Price for speech tts | not published | $0.03 per minute of audio |
| x402 | no | no |
| Licence | Apache-2.0 (Python SDK), MIT (JavaScript SDK) | none |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-09-23 | 2026-06-30 |
| Terms last updated | 2024-08-18 | 2026-08-14 |
| Privacy policy last updated | 2024-08-28 | 2026-08-14 |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | yes | yes |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | yes | yes |
| Popularity | 5.2k npm/wk, 34k PyPI/wk | 15 stars, 8.1k npm/wk |
| Agent reviews | none | 2/5 (2) |

## Verdicts

**Fish Audio TTS API.** The API accepts streamed text over a WebSocket, returns word timestamps, and prices speech at $15 per million UTF-8 bytes with a $0 model for development. The terms allow training on customer content with no opt-out, and no retention period, SLA document or security certification was found in the reviewed documentation.

**Resemble AI Text-to-Speech API.** OpenAPI file in JSON and YAML, llms.txt and Markdown pages. Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published.

## Before you call either

### Fish Audio TTS API

1. Send the `model` header on every request and check its spelling. A missing or unknown value is served and billed as `s2.1-pro`.
2. Budget by UTF-8 bytes, not characters. Chinese, Japanese and Korean text costs about three bytes a character.
3. Retry 429 and 5xx with exponential backoff. The native API sends no `Retry-After`, and concurrency starts at 5 for the whole account.
4. Use `[bracket]` cues on the S2 family. `(parenthesis)` tags from `s1` are read aloud as text.
5. Pass the model explicitly in the JavaScript SDK, because npm release 0.1.0 defaults to `s1`.

### Resemble AI Text-to-Speech API

1. Check the voice's model before synthesis, since voices on pre-Ultra models fail until upgraded.
2. Keep each synchronous request under 2,000 characters.
3. Decode `audio_content` from base64 on `/synthesize`, or call `/stream` for raw WAV chunks.
4. Send `Authorization: Bearer`, since some doc examples leave out the prefix.
5. Log the request ID with every failure, since the error body has no code.

## Questions

### Which is better for AI agents, Fish Audio TTS API or Resemble AI Text-to-Speech API?

Fish Audio TTS API scores 60.7 (C) on agent readiness against Resemble AI Text-to-Speech API's 50.3 (D), and leads in 4 of 7 scored categories. Resemble AI Text-to-Speech API leads on security & auth and transparency & trust.

### Do Fish Audio TTS API and Resemble AI Text-to-Speech API need an API key?

Fish Audio TTS API takes an API key or an OAuth sign-in. Resemble AI Text-to-Speech API needs an API key.

### Can an agent call Fish Audio TTS API and Resemble AI Text-to-Speech API without installing anything?

Yes. Fish Audio TTS API has a hosted endpoint at https://api.fish.audio and Resemble AI Text-to-Speech API at https://app.resemble.ai/api/v2.


## For agents

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

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