> 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. # Models > Find detailed description of each model along with their capabilities and supported languages. ## Text to Speech (TTS) Models #### [Lightning v3.1 Pro](/models/model-cards/text-to-speech/lightning-v-3-1-pro) Latest Release Premium 44 kHz pool with improved naturalness and a curated voice catalog across American, British, and Indian accents. English + Hindi with code-switching, plus 27 additional languages (9 Indian, 8 Asian & Middle Eastern, 10 European) with dedicated Pro voices. Same latency profile as standard Lightning v3.1; select via `"model": "lightning_v3.1_pro"` on the unified TTS routes. #### [Lightning v3.1](/models/model-cards/text-to-speech/lightning-v-3-1) A 44 kHz model delivering natural, expressive, and realistic speech. Supports voice cloning with ultra-low latency. 12 languages (English, Hindi, Spanish, and 9 Indian languages). **Lightning v2 is deprecated.** New integrations should use Lightning v3.1 or Lightning v3.1 Pro. The v2 endpoints remain available for existing callers but are not recommended for new work. ## Speech to Text (STT) Models #### [Pulse Pro](/models/model-cards/speech-to-text/pulse-pro) Latest Release English STT tied for #2 on the public Open ASR Leaderboard (5.42% ESB avg WER). Pre-recorded HTTP only. Select via `?model=pulse-pro` on `POST /waves/v1/stt/`. #### [Pulse](/models/model-cards/speech-to-text/pulse) Low-latency multilingual speech recognition for real-time and pre-recorded transcription. Regional auto-detect aggregators for unknown-language audio. Select via `?model=pulse` on `POST /waves/v1/stt/` or `WS /waves/v1/stt/live`. See the [Pulse model card](/models/model-cards/speech-to-text/pulse) for the supported-language matrix. ## LLM Models #### [Electron](/models/model-cards/llm/electron) Latest Release Smallest AI's in-house language model. OpenAI-compatible chat completions, \<300 ms TTFT, 70 languages with first-class Indic support, voice-agent-optimized tool calling, and automatic prefix caching for repeated input. Select via `"model": "electron"` on `POST /waves/v1/chat/completions`. ## Speech to Speech (S2S) Models #### [Hydra](/models/model-cards/speech-to-speech/hydra) Latest Release Smallest AI's full-duplex speech-to-speech model. Audio in, audio out, over a single WebSocket — no STT → LLM → TTS pipeline in the middle. Phone-grade latency with built-in barge-in, six voices, tool calling. English only today. Select via `?model=hydra` on `WSS /waves/v1/s2s`. Click on a model name to view its detailed model card. API language fields use [ISO 639-1 language codes](https://en.wikipedia.org/wiki/List_of_ISO_639_language_codes) (2-letter). ## Pricing Our pricing model is designed to be flexible and scalable, catering to different usage needs. For detailed pricing information, please visit our [pricing page](https://smallest.ai/pricing) or contact our sales team at [support@smallest.ai](mailto:support@smallest.ai).