Overview
The Lightning TTS API converts text into natural speech via https://api.smallest.ai/waves/v1. 217 voices across 12 languages, 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. 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. Supports 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.
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.
12 Languages
Multilingual support — English, Hindi, Spanish, and 9 Indian languages (Marathi, Kannada, Tamil, Bengali, Gujarati, Telugu, Malayalam, Punjabi, Odia). See the Lightning v3.1 model card for the per-language voice count.
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. For other languages, use standard Lightning v3.1.
For per-language voice counts, see the Lightning v3.1 model card.