> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# TTS language surface aligned with product-team canonical

> The unified TTS endpoints (POST /waves/v1/tts + wss://api.smallest.ai/waves/v1/tts/live) now document the full language surface the platform accepts.

The unified TTS endpoints (`POST /waves/v1/tts` + `wss://api.smallest.ai/waves/v1/tts/live`) now document the full language surface the platform accepts, matching the product-team lineup for both `lightning_v3.1` (base) and `lightning_v3.1_pro`.

**Added to the `language` enum on both HTTP and WebSocket:**

* `auto` - routes the request internally based on input text. Any English or Hindi voice can be used across all supported languages when `auto` is set; the platform handles language-appropriate routing without needing an explicit code per call. Recommended for cross-language use cases.
* `nl` (Dutch) - accepted on both `lightning_v3.1` and `lightning_v3.1_pro`.
* `sv` (Swedish) - accepted on both `lightning_v3.1` and `lightning_v3.1_pro`.

**Updated counts:**

* `lightning_v3.1` accepts **20 language codes** (was documented as 12): 10 European (English, Spanish, French, German, Italian, Dutch, Swedish, Portuguese, Polish, Russian) + 10 Indic (Hindi, Marathi, Gujarati, Punjabi, Bengali, Odia, Tamil, Telugu, Kannada, Malayalam). The trained voice catalog covers 12 of these directly; the remaining 8 route through English or Hindi voices.
* `lightning_v3.1_pro` accepts **31 language codes** (was documented as 29): the 20 above plus 3 additional European (Greek, Finnish, Norwegian) and 8 Asian & Middle Eastern (Chinese, Japanese, Korean, Indonesian, Malay, Vietnamese, Turkish, Arabic).

**No breaking changes** - existing codes still behave identically. `auto`, `nl`, and `sv` were already accepted by the platform; this update documents them.

The Lightning v3.1 and Lightning v3.1 Pro [model cards](/model-cards/text-to-speech/lightning-v-3-1) have the full per-model language breakdown and voice-count tables.