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ElevenLabs is a voice-only provider: it exposes text-to-speech and speech-to-text behind the standard /v1/audio/speech and /v1/audio/transcriptions endpoints. It has no chat, /responses, or embeddings API, so those endpoints return invalid_request_error for ElevenLabs-routed models.

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Configure

Or in config.yaml:

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Voices are IDs, not names

Unlike OpenAI’s fixed voice names (alloy, verse, …), ElevenLabs has no built-in named voices — every voice is an ID from your ElevenLabs voice library (built-in, cloned, or shared). Pass that ID as the OpenAI-compatible voice field:
List your available voice IDs from the ElevenLabs dashboard, or via passthrough (once elevenlabs is added to ENABLED_PASSTHROUGH_PROVIDERS) at /p/elevenlabs/v2/voices — the newer GET /v2/voices search endpoint. /p/elevenlabs/v1/voices does not currently work: GoModel’s provider-passthrough router treats a leading v1/ segment in the path as an alias for providers whose base URL already embeds /v1 (e.g. OpenAI), and strips it before forwarding. ElevenLabs’ base URL is https://api.elevenlabs.io with no /v1, so every /p/elevenlabs/v1/... passthrough call currently 404s. This affects all of ElevenLabs’ native /v1 surface via passthrough, not just voice listing — see “Not implemented” below.

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Supported speech formats

response_format accepts mp3 (default), opus, pcm, and wav; each maps to a fixed ElevenLabs output_format (mp3_44100_128, opus_48000_128, pcm_44100, wav_44100). aac and flac are not supported and return invalid_request_error. speed, when set, is clamped to ElevenLabs’ 0.7-1.2 voice setting range (OpenAI accepts 0.25-4.0); instructions is not supported.

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Speech-to-text models and timestamps

Transcription models (scribe_v2, current; scribe_v1, still valid) are a separate model family from the text-to-speech catalog and are not returned by ElevenLabs’ /v1/models listing — GoModel adds them to /v1/models output itself. response_format accepts json (default), text, and verbose_json; srt/vtt are not supported. Requesting verbose_json, or word in timestamp_granularities, asks ElevenLabs for word-level timing, which GoModel maps into the OpenAI words array. prompt is not supported.

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Not supported by ElevenLabs

All of these return invalid_request_error rather than silently dropping the option:
  • Chat completions, /v1/responses, and embeddings.
  • Speech instructions, and response_format values other than mp3/opus/pcm/wav.
  • Transcription prompt, and response_format values other than json/text/verbose_json.

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Not implemented

GoModel only implements the two ElevenLabs capabilities that map onto OpenAI-compatible endpoints: text-to-speech and speech-to-text. Everything else ElevenLabs offers has no typed support in GoModel today:
  • Speech-to-speech (voice changer) — POST /v1/speech-to-speech/{voice_id} has no OpenAI-compatible equivalent to translate from, so there’s no typed endpoint for it. It could be added as a native passthrough route in the future, but passthrough for it does not currently work either — see the /v1 alias limitation above; speech-to-speech has no /v2 path to work around it with, so it is entirely unreachable through GoModel right now.
  • Dubbing, voice cloning/design, projects (Studio), and conversational AI (agents) — same reasoning: no OpenAI-compatible shape to translate to, and (for the /v1-only parts of these APIs) the same passthrough limitation applies. These are reasonable candidates for future native passthrough support once that limitation is fixed.
  • Realtime/streaming TTS and STT (/v1/text-to-speech/{voice_id}/stream, WebSocket streaming) — GoModel’s /v1/audio/speech and /v1/audio/transcriptions are synchronous request/response; no streaming variant is implemented for ElevenLabs.
None of this is ElevenLabs-specific scope creep avoidance — it reflects that GoModel’s audio surface is deliberately OpenAI-shaped, and ElevenLabs’ API is much larger than OpenAI’s TTS/STT pair.
Last modified on August 10, 2026