Three frameworks, three jobs they do best
The deep learning landscape is no longer winner-takes-all. As of 2026, three major systems share the field, each owning a niche the others struggle in.
| Framework | Owns | Pain Point |
|---|---|---|
| TensorFlow 2.x | Production deployment (TF Serving, TFLite/LiteRT, TF.js, Vertex AI) | Slower research-paper turnaround than PyTorch |
| PyTorch | Research papers, HuggingFace ecosystem, dynamic graphs | Production deployment story is younger |
| JAX | TPU-scale training, functional transforms (jit, grad, vmap, pmap) | Deployment requires a jax2tf bridge |
If you're fine-tuning an LLM the authors released on HuggingFace, you'll be in PyTorch. If you're shipping a phone app that needs on-device inference, you'll be in TensorFlow (TFLite). If you're training Gemini-class models on a TPU pod inside Google, you'll be in JAX. Most production teams use both TF and PyTorch — train where the ecosystem is friendliest, deploy where the runtime is most mature.
Keras 3 changes the calculus. Released late 2023, Keras 3 is a complete rewrite that runs as a high-level API on top of TF, PyTorch, and JAX. You write the model once, set os.environ["KERAS_BACKEND"], and it runs on whichever engine you point it at. The skill you build in this quest transfers across all three.