Voice Models Catalog

Xantly exposes 33 voice models across 6 providers. Use the stt_model / tts_model parameters on the voice endpoints to pick a specific model, or let Xantly auto-route based on language and latency budget.

All models route through the same API key as chat, there is no separate voice subscription. Voice usage bills at exact provider cost (per minute for audio, per character for synthesis), drawn from the same prepaid credit balance. See voice-agents guide for the billing breakdown.

Speech-to-Text (STT), 10 models

Use with POST /v1/voice/transcribe or as stt_model on POST /v1/voice/chat.

Text-to-Speech (TTS), 13 models

Use with POST /v1/voice/synthesize or as tts_model on POST /v1/voice/chat.

Realtime (bidirectional audio), 3 models

Use with GET /v1/voice/realtime (WebSocket upgrade).

Audio LLMs, 7 models

Text + audio input, text + audio output. Use via POST /v1/chat/completions with audio content parts, or via the voice endpoints.

Music Generation, 2 models

Text → audio (music). Use via POST /v1/chat/completions with the model slug.

Speech-to-Speech, 1 model

Audio → audio transformation (voice conversion).

Auto-routing defaults

If you omit stt_model / tts_model, Xantly auto-routes:

• STT: English → deepgram/nova-2, other languages → openai/whisper-1
• TTS: bedrock/gpt-oss-120b-1/us-east-1 by default, or ElevenLabs/Deepgram/Groq when provider is set on the request

Key rotation and fallback

All models that go through OpenRouter, NVIDIA, or Groq use round-robin key rotation across your configured API key pool (e.g. GROQ_API_KEY_1..6). On a per-key 402 / 429, requests automatically waterfall to the next key in the pool. See reliability guide for details.

Usage example

# Transcribe with Groq Whisper (cheapest STT)
curl -X POST https://api.xantly.com/v1/voice/transcribe \
  -H "Authorization: Bearer $XANTLY_API_KEY" \
  -F "audio=@input.wav" \
  -F "stt_model=groq/whisper-large-v3-turbo"

# Synthesize with ElevenLabs Flash (low-latency TTS)
curl -X POST https://api.xantly.com/v1/voice/synthesize \
  -H "Authorization: Bearer $XANTLY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "Hello from Xantly",
    "model": "elevenlabs/eleven_flash_v2_5",
    "voice": "21m00Tcm4TlvDq8ikWAM",
    "output_format": "pcm_16000"
  }' --output hello.pcm

# Full pipeline with explicit STT + TTS picks
curl -X POST https://api.xantly.com/v1/voice/chat \
  -H "Authorization: Bearer $XANTLY_API_KEY" \
  -F "audio=@question.wav" \
  -F "stt_model=groq/whisper-large-v3-turbo" \
  -F "tts_model=deepgram/aura-2"