Applications
You've learned the fundamentals, seen the canonical architectures, and scaled a training run. This section is where it all pays off: small, self-contained implementations of real model families you can build with Flax NNX — each one runnable, each one teaching a distinct idea.
Every guide here follows the same recipe: the math in a few lines, a from-scratch model in idiomatic NNX, a training step, and results you can reproduce. Datasets are tiny (MNIST, synthetic, or built-in) so everything runs on a laptop.
The domains
🎨 Generative Models
Learn to generate data, not just classify it: autoencoders, VAEs, GANs, and
diffusion models. Showcases nnx.ConvTranspose for learned upsampling.
🔁 Sequence Models & Time Series
Recurrence and order: RNNs, LSTMs, and GRUs via the nnx.RNN API family, plus
sequence-to-sequence and forecasting.
🔬 Graphs, Scientific & Structured
Beyond grids and sequences: graph neural networks, physics-informed networks (PINNs) that differentiate through the model, Neural ODEs, tabular data, and mixture-of-experts.
🖼️ Advanced Vision
Vision beyond CNNs: the Vision Transformer (attention on image patches) and the U-Net for dense per-pixel segmentation.
🧬 Multimodal & Adaptation
Adapt and combine models: parameter-efficient fine-tuning with LoRA
(nnx.LoRALinear) and cross-modal alignment.
Prerequisites
These guides assume you're comfortable with the training loop and Flax NNX state. Individual guides link the specific extra background they need.
How to use this section
Each sub-category has a suggested reading order that builds one idea at a time (e.g. Autoencoder → VAE → GAN → Diffusion). Jump straight to a domain that interests you, or work through a whole track.
Next steps
- Start with Generative Models — the most popular track.
- Or explore Sequence Models if you work with text or time series.
- Need to scale one of these up? See Distributed Training.