Watch a neural network learn in real time. As backpropagation adjusts its weights, the decision boundary bends to separate the two classes.
Neural Network PlaygroundLive
2-layer MLP · live backprop
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A tiny multilayer perceptron trained by real backpropagation. The background shows its learned decision boundary; dots are the training data, colored by true class.
Reading this result: With 8 hidden units the net bends the boundary into curves — more units capture finer shapes like the spiral, but too many can overfit.
Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.
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How it works
This is a genuine two-layer perceptron trained by gradient descent and backpropagation, right in your browser. The colored background is the network output at every point; the dots are training data. Change the dataset, hidden-layer size, and learning rate to see how each shapes learning.
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The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this neural network playground tool really free?▾
Yes. Neural Network Playground runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?▾
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?▾
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?▾
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.