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

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.

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.