Fish Audio

Fish Audio builds the text-to-speech models that quietly power voice features inside HeyGen, Retell, Sanas, and other AI products, and it also ships that same technology as a standalone playground and API. Its newer flagship model, S2.1 Pro, adds in-text emotion tags, marking a line as angry, whispering, or laughing, ultra-low latency, and support for 30-plus languages, built on top of the S1 lineage that was trained on more than 2 million hours of audio and hit a 0.8% word error rate on the Seed TTS benchmark. Voice cloning needs as little as 10 to 30 seconds of reference audio with no separate training step.

A $52M seed round in late July 2026 confirmed real traction: 8M-plus users and roughly $21M in annualized revenue at seed stage, unusually strong numbers for a company still raising its first institutional round. The API is pay-as-you-go from the first call, priced at $15 per million UTF-8 bytes of input text with no seat fees or minimum commitment, and a free-tier model variant exists for testing and prototyping without production guarantees. For teams that need to self-host, Fish Audio's core models ship as open weights under a paid commercial license (three of its five released models are fully open-source), deployable in a private VPC, on-prem, or air-gapped environment.

The consumer-facing playground adds credit-based subscription plans with unlimited public voice slots on every tier, making it accessible for solo creators as well as engineering teams shipping voice into their own product.