Nari Qwen3-TTS and Qwen3-ASR – High accuracy, low latency and cost

Hey HN, Toby from Nari Labs here.We've been working on making OSS speech models super-fast. Last year, we built Dia, the first OSS text-to-speech model capable of doing natural dialogue. Since then, so many more great speech models have been released to the public.But the market is still dominated by closed source models. We think that's an inference problem. Existing systems such as vLLM / SGLang are not well suited for multimodal inference. To prove this, we built an inference engine specialized for Qwen3-TTS and open-sourced it (https://github.com/nari-labs/nari-qwen3-tts). Running at sub-50 ms latency at 10 RPS, this showed open models can be run much faster and cheaper.Since then, we've been working hard to bring cheap, fast, and high quality serving to all. And we've even beat closed models at their game!Measured on the highly cited Coval (YC S24) voice AI benchmarks, our Qwen3-TTS endpoint not just is #2 in latency, but #1 in accuracy (WER) compared to 11Labs, Cartesia etc. while being the cheapest endpoint. Our Qwen3-ASR endpoint has the lowest latency and #2 accuracy, just 0.1% away from #1. It is the second cheapest model on the list.It took a lot of clever inference engineering to make these models quick, perform well while keeping costs low. Interestingly, Alibaba's official endpoints seem to perform worse in terms of accuracy and latency compared to ours. But nonetheless, much love to the Qwen team for OSS-ing these amazing speech models.We want to continue to push prices down to make speech technology a commodity - so that every app can have great TTS and STT without worrying about unit costs. We're also working on other parts of audio such as diarization - as well as video and world model inference. More to come!

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FL score

72

out of 100

Verdict

VALIDATE

high confidence

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Inference optimization layer for open-source speech models that undercuts closed competitors on latency, accuracy, and cost.

The pain

Companies building voice features face a choice: pay premium prices to Eleven Labs or OpenAI for reliable TTS/ASR, or deploy open models that are slow, expensive to run, and require deep infrastructure expertise. The latency and accuracy gaps make open models feel unusable for production.

The gap

Existing inference engines (vLLM, SGLang) weren't built for multimodal workloads. Alibaba's own endpoints underperform their models. No one has optimized the full stack—hardware selection, batching strategy, quantization, routing—specifically for speech inference at scale.

Build angle

Nari has already proven the technical thesis: their Qwen3-TTS beats 11Labs on accuracy while costing less, and their ASR is fastest in class. They've moved past 'can we do this' to 'we're already doing this better.' The business model is straightforward: charge per API call at 30-50% of incumbent pricing, capture price-sensitive customers and new use cases that couldn't afford speech before.

Strengths

  • Benchmarked proof of superiority on neutral third-party metrics (Coval), not internal tests
  • Already operating endpoints at scale with real performance data, not a prototype
  • Clear unit economics advantage: cheaper to run than competitors, can undercut pricing and still be profitable
  • Timing: Qwen3 just released, market hasn't optimized for it yet, first-mover advantage in inference
  • Extensible platform: diarization, video, world models mentioned suggest they can expand TAM
  • Open-source components lower barrier to adoption and build community moat

Risks

  • Model performance is a moving target—if Alibaba or OpenAI optimize their inference, the latency/cost advantage shrinks
  • Dependent on open-source model releases; if Qwen stops improving or loses adoption, the business loses its technical foundation
  • Sales and distribution are hard; existing customers have switching costs and relationships with incumbents
  • Inference optimization is a commodity skill—larger players (AWS, Google, Anthropic) could replicate this in weeks if they prioritize it
  • Pricing pressure: if they undercut incumbents, incumbents can match or undercut them back; race to zero margin
  • Regulatory/licensing: unclear if Alibaba's model license permits commercial inference optimization and resale
  • Customer acquisition cost could be high if they need to educate market on open-source speech quality

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