How We Made Our Text-to-Speech API Free: The Inference Engineering Behind S2.1 Pro

Fish Audio's S2.1 Pro, a free text-to-speech API, offers significant advancements in GPU efficiency and cost-effectiveness by optimizing its entire inference stack, which includes custom CUDA kernels, FP8 quantization, and continuous batching. This optimization reduces the hardware requirements to a single GPU for workloads that previously needed four, making the free tier economically viable. The same technology that supports their voice cloning API, which maintains high speaker consistency and performance across 83 languages, is integrated into this offering. By owning their infrastructure and optimizing GPU scheduling, Fish Audio achieves approximately 90% GPU utilization, lowering the cost per request and enabling free access without compromising on quality or performance. Their open-source library, fish-scales-ops, and published benchmarks reflect a commitment to transparency and community engagement in the TTS space.

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