Cartesia
Low-latency TTS with streaming APIs and custom voices (Sonic series)—a go-to layer for natural-feeling voice agents and audio products.
Best for
Low-latency, natural TTS for voice agents, audiobooks, and accessibility; products that want custom brand voices.
Less ideal when
Simple pre-recorded audio use cases, or teams requiring fully OSS/self-hosted TTS.
When comparing
Vs ElevenLabs / Play.ht / OpenAI TTS: Cartesia leads on latency/streaming; ElevenLabs on voice marketplace/custom voices; OpenAI TTS on quick integration.
Quick checklist
- Test streaming latency and barge-in behaviour
- Clear licensing around voice cloning
- Check multi-language and emotion controls
- Plan concurrency pricing and fallback vendors
Search-driven Q&A
Which TTS for a voice agent?
Cartesia is popular when end-to-end latency with STT+LLM matters most; ElevenLabs wins on voice catalogue; OpenAI TTS is easiest to drop into an existing OpenAI stack. A/B recordings of the same script give the clearest picture.
When to use it
The summary should help you decide if this tool fits your needs. When many options look similar, consider how often you’ll use it, budget, and data privacy before choosing one.