apixly.ai

Speech synthesis (TTS)

Text-to-speech (TTS) turns text into generated audio through POST /v1/audio/speech. Async submission is recommended.

Endpoint and API key

POST /v1/audio/speech · Authorization: Bearer YOUR_API_KEY · Audio

Use async: true for both STT and TTS. Submission returns task_id; poll the task without keeping the original connection open. Synchronous models also support async submission.

Supply model and input. Voice, language, reference audio and emotion parameters depend on the model; GET /v1/audio/config lists current parameters. See /models for character, request or second billing and current prices.

bash
curl --max-time 190 "https://apixly.ai/v1/audio/speech" -H "Authorization: Bearer YOUR_API_KEY" -H "Idempotency-Key: UNIQUE_GENERATION_ID" -H "Content-Type: application/json" -d '{"model":"Qwen3-TTS","input":"Hello!","voice":"Ryan","language":"English","response_format":"mp3","async":true}'

Async tasks

Use async: true for both STT and TTS. Submission returns task_id; poll the task without keeping the original connection open. Synchronous models also support async submission.

A model that requires asynchronous execution rejects synchronous requests with 400 async_required before creating an upstream task or charging. Check GET /v1/audio/config for supported execution modes.

waiting means queued; in_progress means processing; only success confirms completion. TTS audio is in output.result or output.file_url; STT results are in output.transcription. Download audio before expires_at.

Use a unique Idempotency-Key per generation. After a disconnect, reuse the original key and identical parameters or query task_id. Cancelling an unstarted queued task releases its reservation; submitted tasks need confirmed cancellation. unknown is not a confirmed free failure: keep the task ID and check with support.

bash
curl "https://apixly.ai/v1/task/TASK_ID" -H "Authorization: Bearer YOUR_API_KEY"
bash
curl -X POST "https://apixly.ai/v1/task/TASK_ID/cancel" -H "Authorization: Bearer YOUR_API_KEY"

Billing

Submission reserves the estimated fee at the model price, billing unit and discount fixed for this task. Queuing is not final charging. Completed work is settled once; the final USD amount appears in usage.cost_request and usage records.

Response examples

waiting means queued; in_progress means processing; only success confirms completion. TTS audio is in output.result or output.file_url; STT results are in output.transcription. Download audio before expires_at.

TTS parameters and model-specific options

Supply input (1–10000 Unicode characters), or model-supported inputs[] (1–32 prompt objects), never both. Qwen3-TTS voices: Vivian, Serena, Uncle_Fu, Dylan, Eric, Ryan, Aiden, Ono_Anna, Sohee; language Chinese (default) or English. response_format: mp3/wav; url requests a URL result, with response_data_format=url as an alternative. Use returned expires_at, not a hard-coded download lifetime.

Voice cloning: prompt_audio_url is required by reference-based models; CosyVoice2/3 and Step-Audio-TTS-3B also need prompt_text. Reference URLs must be public HTTP(S). IndexTTS-2 emotion controls: emo_text, use_emo_text, emo_alpha (0–1), emo_vector (8 values, each 0–1), emo_audio_prompt_url. ChatTTS: temperature, top_P, top_K. speed is usually 0.5–2; CosyVoice3 and Spark-TTS-0.5B use 1–5. Aliases speaker→voice, prompt_wav_url→prompt_audio_url, instruction/instruct_text→instructions, output_format→response_format, top_p/top_k→top_P/top_K must not conflict. All options depend on the model contract; check /v1/audio/config.

Additional model options

ChatTTS: voice_url is a public HTTP(S) voice-feature URL. Spark-TTS-0.5B: gender=male/female and pitch=1–5. CosyVoice2/3: seed accepts an integer or integer string. Support is model-specific; a fixed seed does not guarantee identical audio.

Model-specific request contracts

Discover available IDs with GET /v1/models using your key. The public price catalog is not a guarantee of current routing. Existing valid requests need no changes; optional fields are model-specific.

Existing valid single-input requests do not need changes. Use input for ChatTTS, CosyVoice2, GLM-TTS and Step-Audio-TTS-3B and send each generation as a separate request. async:true gives a durable task; it does not add batch support to a synchronous-only model. Multi-item inputs[] are now rejected before supplier submission for those models, rather than merging the texts and quoting multiple request charges.

IndexTTS-2 and GLM-TTS require prompt_audio_url. GLM-TTS prompt_text is optional. The current GLM-TTS provider rejects requests without reference audio; supply the URL even though its published schema marks it optional. CosyVoice2/3 and Step-Audio-TTS-3B require both prompt_audio_url and prompt_text. Spark-TTS-0.5B has a gender/pitch/speed mode and a reference-audio mode; pitch/speed use1–5. All model access is subject to GET /v1/models with your key.

  • ChatTTS
  • CosyVoice2
  • CosyVoice3
  • GLM-TTS
  • IndexTTS-2
  • Qwen3-TTS
  • Spark-TTS-0.5B
  • Step-Audio-TTS-3B
bash
curl --max-time 190 "https://apixly.ai/v1/audio/speech" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"GLM-TTS","input":"你好，这是一个语音测试。","prompt_audio_url":"https://your-server.example.com/reference.mp3","response_format":"mp3"}' \
  --output speech.mp3