Models

Available models

Pass the model ID as the model parameter in your API calls. If omitted, the API defaults to simba-3.0; we recommend explicitly setting model: "simba-3.2" on English-only integrations for the lowest TTFB and richest expressivity.

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curl -X POST https://api.speechify.ai/v1/audio/speech \
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     -H "Authorization: Bearer <token>" \
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     -H "Content-Type: application/json" \
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     -d '{
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  "input": "Hello! This is the Speechify text-to-speech API.",
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  "voice_id": "geffen_32",
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  "audio_format": "mp3",
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  "model": "simba-3.2"
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}'

Listing models via the API

Fetch the current set of selectable models at runtime instead of hardcoding the table above. GET /v1/audio/models returns every model ID you can pass as the model parameter, marks the default (the model used when model is omitted) and the recommended model, and describes each one. Drive a model picker from this response so it stays current as models are added or the recommendation changes.

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curl https://api.speechify.ai/v1/audio/models \
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     -H "Authorization: Bearer <token>"

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{
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  "models": [
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    {
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      "id": "simba-english",
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      "name": "Simba English",
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      "default": false,
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      "recommended": false,
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      "deprecated": true,
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      "description": "Legacy Simba 1.6 English model, kept for compatibility. Prefer simba-3.2.",
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      "languages": [
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        "en"
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      ],
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      "endpoints": [
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        "/v1/audio/speech",
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        "/v1/audio/stream"
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      ],
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      "curated_voices": false,
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      "english_voices_only": false
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    },
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    {
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      "id": "simba-multilingual",
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      "name": "Simba Multilingual",
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      "default": false,
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      "recommended": false,
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      "deprecated": true,
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      "description": "Legacy Simba 1.6 multilingual model covering 30+ languages, including mixed-language input. Prefer simba-3.0 for the languages it supports.",
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      "languages": [
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        "en",
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        "fr-FR",
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        "de-DE",
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        "es-MX",
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        "pt-BR",
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        "ja-JP"
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      ],
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      "endpoints": [
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        "/v1/audio/speech",
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        "/v1/audio/stream"
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      ],
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      "curated_voices": false,
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      "english_voices_only": false
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    },
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    {
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      "id": "simba-3.0",
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      "name": "Simba 3.0",
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      "default": true,
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      "recommended": false,
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      "deprecated": false,
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      "description": "Streaming-native synthesis in English and six European languages, routed by the request `language`. The default when a request omits `model`.",
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      "languages": [
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        "en",
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        "de-DE",
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        "es-ES",
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        "es-MX",
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        "fr-FR",
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        "it-IT",
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        "pt-BR"
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      ],
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      "endpoints": [
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        "/v1/audio/speech",
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        "/v1/audio/stream",
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        "/v1/audio/stream/with-timestamps"
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      ],
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      "curated_voices": false,
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      "english_voices_only": false
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    },
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    {
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      "id": "simba-3.2",
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      "name": "Simba 3.2",
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      "default": false,
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      "recommended": true,
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      "deprecated": false,
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      "description": "Streaming-native model with the lowest time-to-first-byte and richest expressivity, English only today. Serves the curated voice roster, plus your workspace's own cloned voices where cloning has been enabled for it.",
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      "languages": [
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        "en"
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      ],
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      "endpoints": [
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        "/v1/audio/speech",
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        "/v1/audio/stream",
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        "/v1/audio/stream/with-timestamps"
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      ],
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      "curated_voices": true,
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      "english_voices_only": true
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    }
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  ],
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  "dialogue_models": [
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    {
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      "id": "simba-dialogue-1.0",
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      "name": "Simba Dialogue 1.0",
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      "default": true,
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      "recommended": false,
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      "deprecated": false,
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      "description": "Multi-speaker model that renders a speaker-attributed script as one conversation with natural turn-taking.",
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      "languages": [
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        "en"
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      ],
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      "endpoints": [
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        "/v1/audio/dialogue"
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      ],
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      "curated_voices": false,
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      "english_voices_only": true
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    }
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  ]
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}

Each entry carries the model id, a human-readable name and description, a default flag, a recommended flag (the model we suggest for new integrations, which is distinct from the default - the default accepts every voice, while the recommended model may serve a curated or English-only set), a deprecated flag, and the languages it can synthesize (BCP-47 locale strings matching the language parameter). deprecated marks a legacy model; it is advisory only - a deprecated model stays fully supported and behaves exactly as before, with nothing scheduled for removal, so treat the flag as a cue to de-emphasise the model in a picker and steer new integrations elsewhere. These values reflect current support and can change over time - a model may gain languages, for example - so read them at runtime rather than caching them: because the response shape is stable and clients ignore unknown fields, both changing values and future new fields are picked up without breaking existing integrations.

Voice cloning is not advertised per model here because whether cloned voices are available also depends on your plan; see Voice Cloning.

Simba 3.2

Streaming-native flagship model with the lowest TTFB (time to first byte) and richest expressivity. Recommended for new English integrations.

• Optimized for real-time streaming with the lowest startup latency
• Richer expressive range than earlier Simba generations
• Full support for SSML and emotion control
• Serves a curated stock voice set: beatrice_32, dominic_32, edmund_32, geffen_32, harper_32, hugh_32, imogen_32, wyatt_32
• English only; a non-English voice returns 400. Use simba-3.0 for the other supported languages
• Zero-shot voice cloning is supported: your workspace’s own cloned voices work here alongside the curated set. Currently a limited release enabled per workspace — see Voice Cloning

Simba 3.0

Streaming-native model covering English plus six European languages. The model a request resolves to when it omits model.

• Officially supports en-*, de-DE, es-ES, es-MX, fr-FR, it-IT and pt-BR. See Language Support
• Set the language parameter to pick the language; when omitted, the voice’s own locale decides
• English and non-English are served by two separate trainings, but that routing is internal: the model ID you pass is always simba-3.0
• Languages outside the supported set often work but are not validated; use simba-multilingual for the full 30+ locale set
• Prefer simba-3.2 for English-only integrations; it has lower TTFB and richer expressivity
• Full support for SSML and emotion control
• Zero-shot voice cloning works self-serve, in every language the model supports - see Voice Cloning

Simba Multilingual

Supports multiple languages, including mixing languages within a single sentence.

• 35 locales covering 30 distinct languages live today
• Automatic language detection when the language parameter is omitted
• Zero-shot voice cloning works across all supported languages
• Fine-tuned voice cloning available (contact sales)

See Language Support for the full list.

Simba English

Kept for compatibility with integrations that name it explicitly.

• Full support for SSML and emotion control
• Zero-shot voice cloning from short audio samples
• Fine-tuned voice cloning from hours of speaker audio (contact sales)
• Prefer simba-3.2 for new integrations using the built-in voice catalog

Voice cloning

Simba English and Simba Multilingual support two tiers of voice cloning; Simba 3.0 supports zero-shot cloning self-serve, and Simba 3.2 supports it as a limited release enabled per workspace:

A cloned voice works on simba-3.0, simba-english and simba-multilingual with no approval step. simba-3.2 cloning is enabled per workspace while it rolls out; once your workspace is enabled, every clone you own works there and you pass the voice ID exactly as you would a stock voice. Contact Speechify to be enabled.

See Voice Cloning for implementation details.

FAQ