Keras 3 is a multi-backend deep learning framework that provides a high-level API for building and training neural networks. It supports TensorFlow, JAX, PyTorch, NumPy, and OpenVINO backends, allowing users to switch between them with minimal code changes. The repository contains a comprehensive set of layers (convolutional, recurrent, attention, normalization, pooling, preprocessing, regularization), optimizers (Adam, SGD, AdamW, Lion, etc.), metrics, callbacks, loss functions, and utilities for model saving/loading, quantization, distillation, and distributed training. The architecture is modular with a clean separation between backend-agnostic operations and backend-specific implementations. The codebase is well-tested with extensive unit and integration tests, and includes benchmarks for performance comparison. It is actively maintained with frequent commits and responsive issue triage.

AutoKeras is an automated machine learning (AutoML) library built on Keras 3, designed to make deep learning accessible to non-experts. It provides high-level task-specific APIs (e.g., ImageClassifier, TextClassifier, StructuredDataClassifier) that automate neural architecture search and hyperparameter tuning. The core architecture uses a modular block-based system—blocks (e.g., DenseBlock, ConvBlock, ResNetBlock) are composed into a graph via a functional API, and a tuner (Greedy, Bayesian, Hyperband, Random) searches for the best model. The library includes a data preprocessing pipeline (Pipeline, HyperPipeline), adapters for input/output conversion, and serialization for model persistence. While primarily an application library, it also contains research-oriented components like benchmark experiments and tuner implementations, reflecting its academic origins. Key entry points are the AutoModel class and task classes, which expose fit/predict/evaluate workflows similar to Keras.

KerasHub is a production-grade Keras 3 library providing pretrained model architectures, layers, tokenizers, metrics, and sampling utilities for NLP, vision, multimodal, and audio tasks. The codebase is organized around a consistent Backbone → Task → Preprocessor pattern, where each model family (e.g., BERT, Gemma, ViT, Whisper) defines a backbone, a preprocessor (tokenizer + optional media converter), and task-specific heads (CausalLM, ImageClassifier, etc.). All models expose a unified `from_preset()` API for loading pretrained weights hosted on Kaggle Models, and `save_to_preset()` for export. The library includes extensive checkpoint conversion tooling from HuggingFace and TIMM, export to HuggingFace format and OpenVINO, and integration with vLLM for serving. While predominantly an application library, it has strong data/research character through its pretrained weight infrastructure, benchmark scripts, and research-oriented architectures (e.g., FNet, RWKV7, BLIP-2).