Twitter/X

On 2026-07-29 @DataChaz reports FishAudio released S2.1 Pro, an open-weight TTS…

Brief

FishAudio's S2.1 Pro, announced 2026-07-29 via @DataChaz, is an open-weight TTS model claiming on-prem deployment with zero data retention, 2× speed vs. Cartesia, 1/6th the cost of ElevenLabs, 56.3 chars/s throughput, ~90ms latency, and native support for 83+ languages—features the author says end ElevenLabs' dominance and make it a top open-source option for production voice agents.

Why it matters

On 2026-07-29 @DataChaz reports FishAudio released S2.1 Pro, an open-weight TTS model offering on-prem deployment with zero data retention.

Key details

  • The post states S2.1 Pro is 2x faster than Cartesia, costs 1/6th of ElevenLabs, delivers 56.3 chars/s throughput (ahead of GPT-Realtime-2), supports 83+ languages, and achieves ~90ms latency for natural conversations.
  • Developers get natural-language control over emotion, pacing, and delivery plus real-time performance; the author frames S2.1 Pro as a major competitive threat that ends ElevenLabs' multi-year TTS dominance and the most interesting open-source release for production-grade voice agents.
Source evidence

THE FOUNDERS OF @ELEVENLABS HAVE TO BE SWEATING RIGHT NOW

For years, they absolutely dominated TTS because no open-source options could actually sound human.

That era is officially over.

@FishAudio just dropped their S2.1 Pro model, stepping up as one of the rare voice AI companies offering open-weight models.

Devs now get now natural-language control over emotion, pacing, and delivery, alongside serious real-time performance:

The specs speak for themselves:
→ 2x faster than Cartesia
→ 1/6th the cost of ElevenLabs
→ 56.3 chars/s throughput, ahead of GPT-Realtime-2
→ Native support for 83+ languages
→ Around 90ms latency for natural conversations

Need to keep everything in-house? S2.1 Pro also supports on-prem deployment with zero data retention.

If you're building production-grade voice agents, this is THE most interesting open-source releases to test right now 👀