Gradium
Ultra-low-latency voice AI platform delivering streaming text-to-speech, speech-to-text, and voice cloning through a unified API with credit-based pricing.
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Product Overview
What is Gradium?
Gradium is a Paris-based voice AI platform spun out of the Kyutai research lab, built for developers who need real-time, natural-sounding voice interactions. The platform consolidates text-to-speech (TTS), speech-to-text (STT), voice cloning, and live speech-to-speech translation into a single API stack optimized for WebSocket streaming. Gradium's TTS models achieve sub-250ms time-to-first-audio latency on independent benchmarks, making it suitable for voice agents and conversational applications. The service operates on a flexible credit-based system with a generous free tier and scales from individual developers to enterprise deployments with custom pricing.
Key Features
Ultra-Low-Latency Streaming TTS
WebSocket-based text-to-speech API delivering ~216-235ms time-to-first-audio with incremental audio streaming, enabling natural real-time voice interactions for agents and applications.
Real-Time Speech-to-Text with Semantic VAD
Streaming STT API featuring semantic voice activity detection that intelligently identifies speech boundaries, reducing false transcriptions and improving accuracy for voice agent workflows.
Instant & Professional Voice Cloning
REST API for zero-shot voice cloning from 10 seconds of audio (up to 1,000 clones/month on paid plans), plus fine-tuned Professional Voice Cloning for higher speaker fidelity on M and L tiers.
Unified Credit-Based Pricing
Single credit pool across all services (TTS, STT, cloning) with six tiers from Free (45k credits/month) to Enterprise, plus pay-as-you-go overflow at competitive per-credit rates.
Multilingual & On-Device Support
Core voice capabilities in English, French, Spanish, Portuguese, and German, plus Phonon on-device TTS SDK (100M parameters) for offline mobile deployment with 1.00% WER on Seed-TTS benchmark.
Live Speech-to-Speech Translation
Real-time translation API converting spoken audio in one language to synthesized speech in another, enabling cross-lingual voice agent and communication applications.
Use Cases
- Voice Agents & Conversational AI : Build responsive AI assistants and chatbots with natural voice interactions, leveraging sub-250ms TTS latency and semantic VAD for seamless turn-taking and reduced conversation gaps.
- Real-Time Transcription Services : Deploy live transcription for meetings, podcasts, or customer support calls with streaming STT, custom vocabulary support, and code-switching for multilingual speakers.
- Personalized Voice Experiences : Create branded or personalized voice clones for audiobooks, gaming NPCs, or customer service bots using instant cloning from short samples or professional fine-tuned models.
- Multilingual Content Localization : Translate and synthesize content across five supported languages for global audiences, or use live speech-to-speech translation for real-time cross-lingual communication tools.
- Offline & Edge Voice Applications : Deploy the Phonon on-device TTS SDK for mobile apps, IoT devices, or privacy-sensitive applications requiring offline voice synthesis without API calls or latency concerns.
- Developer Prototyping & Scaling : Start with 45k free monthly credits for testing, then scale through XS to Enterprise tiers with predictable credit pricing and pay-as-you-go overflow for unpredictable usage spikes.
FAQs
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