Speech-to-text inference for the end-to-end purist
A server framework dedicated to running inference on PyTorch transducer and CTC models, leaving the training to its sibling project.

What it does
sherpa is a speech-to-text inference framework built on PyTorch that exclusively serves end-to-end models—specifically transducer and CTC architectures. It provides C++ and Python APIs and focuses strictly on deployment, not training. For fine-tuning or training, it redirects you to its companion project icefall.
The interesting bit
Rather than swelling into a kitchen-sink toolkit, the project acknowledges its PyTorch weight and points to siblings sherpa-onnx and sherpa-ncnn for iOS, Android, and embedded targets. It is a rare case of a project family cleanly partitioned by runtime rather than feature.
Key highlights
- End-to-end only: deliberately ignores classical hybrid pipelines in favor of transducer and CTC models.
- Dual-language APIs: exposes both C++ and Python interfaces for server integration.
- Browser demo: includes a Hugging Face space for zero-installation trials.
- Clear scope boundary: training is explicitly out of scope, with a direct hand-off to
icefall.
Caveats
- The README is minimal; substantive documentation lives on an external site.
- PyTorch dependency makes it a poor fit for mobile or deeply embedded use, though the siblings cover that gap.
Verdict
Useful if you need a PyTorch-native server for modern ASR inference. Look elsewhere—specifically at its onnx or ncnn siblings—if you need lightweight edge deployment, or at icefall if you need to train.
Frequently asked
- What is k2-fsa/sherpa?
- A server framework dedicated to running inference on PyTorch transducer and CTC models, leaving the training to its sibling project.
- Is sherpa open source?
- Yes — k2-fsa/sherpa is open source, released under the Apache-2.0 license.
- What language is sherpa written in?
- k2-fsa/sherpa is primarily written in C++.
- How popular is sherpa?
- k2-fsa/sherpa has 962 stars on GitHub.
- Where can I find sherpa?
- k2-fsa/sherpa is on GitHub at https://github.com/k2-fsa/sherpa.