Neurolume

See your PyTorch and Keras models as interactive diagrams, and watch them train... (If it's working)

Neurolume runs your model once to learn its shape, then opens an interactive viewer in the browser: every layer as a panel, every dense connection as a line, feature maps painted with what the model actually sees. Several models wired together become one schematic you can open level by level. While you train, the same viewer shows the loss, whether the model is overfitting, its predictions against the truth, and how its parameters change, and lets you scrub back through the run.

• One call: neurolume.show(model, sample). No account, no log files, nothing to set up.
• PyTorch and Keras 3, CNNs (with real feature maps), residual and branching models.
• Systems: several networks plus plain blocks (sensors, losses, outputs) in one diagram, nested as deep as you like.
• Live training: a calmer, more readable alternative to TensorBoard, in the browser or embedded in a Qt app.
• Export to one standalone HTML file that opens anywhere, offline.

Install

pip install "neurolume[torch]"      # with PyTorch
pip install "neurolume[keras]"      # with Keras 3, plus a backend: TensorFlow, JAX or PyTorch

Neurolume needs Python 3.10 or later. The viewer runs in any modern browser; nothing else needs installing. (Keras with PyTorch underneath: install torch too and set KERAS_BACKEND=torch.)

Example 1: a model

import neurolume
import torch
from torch import nn


class MLP(nn.Module):
    def __init__(self) -> None:
        super().__init__()
        self.flatten = nn.Flatten()
        self.fc1 = nn.Linear(784, 512)
        self.relu1 = nn.ReLU()
        self.dropout = nn.Dropout(0.2)
        self.fc2 = nn.Linear(512, 256)
        self.relu2 = nn.ReLU()
        self.fc3 = nn.Linear(256, 10)

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        x = self.flatten(x)
        x = self.dropout(self.relu1(self.fc1(x)))
        x = self.relu2(self.fc2(x))
        return self.fc3(x)


neurolume.show(MLP(), (1, 28, 28))  # the shape of one input: 1 channel, 28 x 28 pixels

This opens the viewer shown at the top of this page. Each layer is a panel; the lines between them are the strongest weights, brighter where the weight is larger. Click a layer for its details, scroll to zoom, drag to pan.

The second argument, sample, tells Neurolume what goes into the model:

• the shape of one input, without the batch dimension, like (1, 28, 28). Enough to draw the architecture.
• real data, such as a batch of images. Convolution layers then show their actual feature maps for that input.

Neurolume follows the data through your model's forward method to find the layers and how they connect, so a PyTorch model needs a forward (or must be an nn.Sequential). Keras models that start with keras.Input don't need a sample at all.

Run it: examples/mlp.py.

Example 2: a system of networks

Real projects are often several networks wired together. Add each one, plus any plain blocks such as data sources or losses, and connect them:

import neurolume
from torch import nn


def mlp(*sizes):
    layers = []
    for i, (inputs, outputs) in enumerate(zip(sizes, sizes[1:])):
        layers.append(nn.Linear(inputs, outputs))
        if i < len(sizes) - 2:
            layers.append(nn.ReLU())
    return nn.Sequential(*layers)


system = neurolume.System("Sensor autoencoder")
sensor = system.block("sensor", label="Sensor", description="32 readings per sample", output_shape=[32])
encoder = system.add("encoder", mlp(32, 64, 64, 16), (32,), label="Encoder")
decoder = system.add("decoder", mlp(16, 64, 64, 32), (16,), label="Decoder")
classifier = system.add("classifier", mlp(16, 12, 3), (16,), label="Classifier")
loss = system.block("loss", label="Reconstruction loss", description="Mean squared error", input_shape=[32])
prediction = system.block("prediction", label="Fault type", input_shape=[3])

system.connect(sensor, encoder, label="readings")
system.connect(encoder, decoder, label="latent")
system.connect(encoder, classifier, label="latent")
system.connect(decoder, loss)
system.connect(classifier, prediction, label="logits")

neurolume.show(system)

The viewer opens on an overview: one card per network or block, with labelled links between them. Click a card (or zoom into it) to open its layers; press Esc or zoom out to go back. Blocks can carry Markdown notes with LaTeX maths (notes=...), shown when you click them.

Run it: examples/system.py.

Example 3: systems inside systems

A component can itself be a System, or a model with parts of its own. Each one opens to its own overview, as many levels deep as you need:

import neurolume
from autoencoder import Autoencoder  # a model with self.encoder and self.decoder
from system import build_system      # the System from example 2

plant = neurolume.System("Plant monitor")
camera = plant.block("camera", label="Camera", description="Noisy 28 x 28 frames", output_shape=[1, 28, 28])
denoiser = plant.add("denoiser", Autoencoder(), (1, 28, 28), label="Denoiser")
sensors = plant.block("sensors", label="Sensor bus", description="32 readings per tick", output_shape=[32])
detector = plant.add("detector", build_system(), label="Fault detector")  # a whole System as one component
alarm = plant.block("alarm", label="Alarm", description="Raise a ticket on a fault", input_shape=[3])
display = plant.block("display", label="Operator screen", input_shape=[784])

plant.connect(camera, denoiser, label="frames")
plant.connect(denoiser, display, label="clean frames")
plant.connect(sensors, detector, label="readings")
plant.connect(detector, alarm, label="fault type", from_="prediction")  # the detector has two outputs

neurolume.show(plant)

The "Denoiser" card opens to its encoder and decoder; the "Fault detector" card opens to the whole system from example 2. Links from outside attach to its ends: the readings reach its sensor block, and the fault type leaves from its prediction block. The tree at the bottom left shows every level.

A single PyTorch module that keeps its parts in attributes (self.encoder, self.decoder) is split into networks like this automatically. Pass group_submodules=False to show to keep it as one network.

Run it: examples/nested_system.py.

Watching a model train (beta)

Swap show for watch and log as you go:

live = neurolume.watch(model, (8,))
for step in range(steps):
    loss = train_step()                          # forward, backward, optimiser step
    live.log(step, loss=loss)                    # after backward(); tensors are fine
    if step % 100 == 0:
        live.log(step, split="val", loss=val_loss)
        live.predictions(step, predicted, target)  # e.g. on a validation batch
live.finish()                                    # the viewer stays open until Ctrl+C

The viewer gains a run strip (step, the main metric, its trend) and a Training panel:

• Summary: whether the run is improving, levelling off, converged, getting worse or overfitting (validation getting worse while training still improves), the gap between validation and training, and the best validation point.
• Predictions vs truth: a predicted-against-true scatter with R² and mean error, or a confusion matrix when the targets are class labels.
• Metrics: a chart for each metric you log, with training and validation together. Smooth, log-scale, reorder, hide, combine or pin them; the layout is remembered per model.
• Parameters: the weight norm (how large the weights are overall), the gradient norm, how fast the parameters move, and how their values are spread over time.

The network itself updates too: lines brighten and fade as the weights change (or show the change since the start, or the gradient), and CNN feature maps repaint as the filters learn. Drag the timeline to scrub back through the run. live.save("run.nlrun") keeps it; neurolume.open_run("run.nlrun") opens it again later.

log() costs microseconds; the model is read at most every half second (every_seconds=0.5): about 1% of training time for an MLP, and live feature maps are kept under 2%.

• Keras: model.fit(x, y, callbacks=[neurolume.keras.Live(x[:64], validation=(x_val, y_val))]).
• Systems: neurolume.watch(system) follows every network, nested ones included; live.log(step, network="critic", loss=...) logs per network.

Run it: examples/live_training.py (a small model that overfits on purpose), examples/live_resnet.py (ResNet-18 with live feature maps), examples/live_nested_system.py (example 3's plant monitor, every network training at once), examples/keras_live.py.

Sharing: a standalone HTML file

neurolume.export_html(model, (1, 28, 28), "model.html")
neurolume.export_html(live, path="run.html")   # a training run, with its charts and timeline

One file with the viewer and your model inside. It opens from disk or an email attachment, offline, with no Python. The Export button in the viewer's Settings does the same.

Embedding in a Qt app

from neurolume.qt import NeurolumeWidget  # import before creating the QApplication

widget = NeurolumeWidget(model, (1, 28, 28))
layout.addWidget(widget)
session = widget.watch(model, sample)       # or show a live run, and log() to it

A QWebEngineView with the same viewer, for your own tools and training loggers. Needs pip install "neurolume[qt]" PySide6. See examples/qt_widget.py and examples/qt_live.py (a logger with Start/Stop, training on a background thread).

Viewer controls

Action	Control
Zoom	Scroll
Pan	Drag
Layer or block details	Click
Open a network	Click, or zoom in
Back to the overview	Zoom out, or Esc
Fit to screen	Double-click, or F
Light or dark	T

Settings (top right) has the colour map, the theme, how many neurons and connections to draw, and Export.

How it works

Python runs your model once on the sample (with torch.fx, or Keras's own layer graph) and describes it as a JSON graph: layers, shapes, connections, the strongest weights, feature maps. A small local server (Tornado) hands that graph to a TypeScript and three.js viewer in your browser. During training, the same server streams metrics and weights over a WebSocket. Nothing leaves your machine.

Development

git clone https://github.com/Freddie-Ellis/neurolume
cd neurolume
pip install -e ".[dev,torch]"
pytest

The viewer lives in frontend/ (TypeScript, Vite, three.js; Node 18+). After changing it, rebuild it into the Python package with scripts/build_frontend.ps1 (PowerShell), and run its tests with npm test in frontend/. For live reloading, run neurolume.show(model, x, port=8000) and npm run dev in frontend/.

The JSON schema in python/neurolume/schema.py is the contract between Python and the viewer: after changing it, bump SCHEMA_VERSION and run python scripts/generate_schema_ts.py. The roadmap is docs/project-plan.md.

Licence

MIT. See LICENSE.