Overview
The Lightning TTS API converts text into natural speech via https://api.smallest.ai/waves/v1. 31 languages across two pools — the standard 217-voice Lightning v3.1 catalog (20 accepted codes, 12 with trained voices) and the premium Lightning v3.1 Pro pool (all 31) — plus auto for cross-language routing, at 44.1 kHz native sample rate, ~200ms TTFB, with sync, SSE, and WebSocket streaming.
Hear Lightning v3.1 Pro (voice: meher, model: lightning_v3.1_pro):
Synthesis Modes
Choose the synthesis mode that best fits your application’s needs:
Generate complete audio files with a single HTTP request. Ideal for pre-rendering content, batch processing, and applications where immediate streaming isn’t required.
Receive audio chunks as they’re generated via WebSocket. Perfect for real-time voice assistants, live narration, and low-latency conversational AI.
Available Models
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 29 additional languages (9 Indic, 8 Asian & Middle Eastern, 12 European including Dutch and Swedish) with dedicated Pro voices, plus auto cross-language routing. Same latency profile as Lightning v3.1. Select via "model": "lightning_v3.1_pro" on the unified TTS routes.
44.1 kHz audio output, ~200ms TTFB, expressive human-like speech, and voice cloning. Accepts 20 language codes (10 European + 10 Indic) plus auto; 12 of those languages have a trained voice catalog, the other 8 route via English or Hindi voices.
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.
Feature Highlights
Ultra-Low Latency
Optimized streaming pipeline delivers ~200ms time-to-first-byte (TTFB) for real-time applications. Lightning v3.1 achieves even faster response times for conversational AI.
Voice Cloning
Create custom voice profiles by uploading audio samples. Instant voice cloning works with just a few seconds of audio, while professional voice cloning delivers studio-quality results.
31 Languages + auto routing
31 Languages + auto routing
Lightning v3.1 accepts 20 language codes (10 European: English, Spanish, French, German, Italian, Dutch, Swedish, Portuguese, Polish, Russian + 10 Indic: Hindi, Marathi, Gujarati, Punjabi, Bengali, Odia, Tamil, Telugu, Kannada, Malayalam). Its trained voice catalog covers 12 of these directly; the other 8 route via English or Hindi voices. Lightning v3.1 Pro covers all 31 languages with dedicated voices (adds Greek, Finnish, Norwegian + 8 Asian & Middle Eastern languages). Pass auto to route across any supported language using any English or Hindi voice. See the Lightning v3.1 and Lightning v3.1 Pro model cards for per-language voice counts.
Multiple Output Formats
Choose from PCM, WAV, MP3, or μ-law encoding. Configurable sample rates from 8kHz to 44kHz to match your application’s requirements.
Speed Control
Adjust speech rate with a simple multiplier. Slow down for clarity or speed up for faster content delivery without pitch distortion.
Pronunciation Dictionaries
Define custom pronunciations for brand names, technical terms, and acronyms. Ensure consistent, accurate pronunciation across all synthesized audio.
High-Quality Audio
Lightning v3.1 produces 44 kHz audio with natural prosody and expressiveness. Perfect for audiobooks, podcasts, and premium voice experiences.
WebSocket Streaming
Persistent connections for continuous audio streaming. Ideal for voice bots and interactive applications where latency is critical.
Supported Languages
Pro language support is per voice. Indian Pro voices (e.g., meher, rhea, aviraj) speak English with native Hindi code-switching. British and American Pro voices speak English only. Each additional Pro language has its own dedicated voices — pass the matching ISO 639-1 language code with a voice from that language (see the Pro voice catalog). For languages without Pro voices, use standard Lightning v3.1.
For per-language voice counts, see the Lightning v3.1 model card.