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Learn PyTorch, JAX, Rust, C++ and typed Python by building.
Benchmarked on your own GPU.

1223 problems across JAX, PyTorch, Rust, C++ and typed Python, from Flax and NNX layers to Rust ownership and lifetimes to mypy-checked Python. 85 guided tracks and 242 explainers. Your code runs on your own machine and is timed against a reference implementation.

Start solving Set up the runtime
pip install crackedai-connect Browsing PyTorch. 169 problems in this mode.
Example run 127.0.0.1:52341
mode
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device
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tests
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median
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vs reference —

Five languages, one loop

342

Rust

Ownership, lifetimes, async, unsafe

195

Python

Type hints checked by mypy

169

PyTorch

Autograd, modules, custom kernels

167

JAX

Flax, NNX, sharding, grad transforms

32

C++

Templates, RAII, move semantics, cache lines

There is more here
than you can finish.

1223 problems · 85 tracks · 242 explainers

See the corpus
lora-update.py
Medium Research PyTorch solve → 
import torch

def lora_forward(x: torch.Tensor, W: torch.Tensor, A: torch.Tensor,
             B: torch.Tensor, alpha: float, r: int) -> torch.Tensor:
    """Forward pass with LoRA: h = (W + (alpha/r) * B @ A) @ x."""
    pass

random problem, refresh for another

By category

Primitives

softmax, relu, batch norm, adam

54 problems

Framework

autograd, vmap, einsum, jit

24 problems

End-to-End

MLP, CNN, RNN, transformer

66 problems

Research

RoPE, GQA, LoRA, MoE

25 problems

Not alone

Pick a track, pull in a few friends, and the conversation gets a scoreboard. The chat is end-to-end encrypted; the board is built from who solved what. Neither half can see the other's secrets.

#jax-performance end-to-end
ren the vmap one finally clicked, in_axes strips the axis
you wait, so the function never sees the batch at all?
ren never. that is the whole trick
mika 3 left on this track and I am done

The server stores these as ciphertext. The words above only exist in a member's browser.

Squad board 8 problems
ren 7/8
you 5/8
mika 5/8
sam not sharing

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Start a squad on a track Find friends

How it runs

$ crackedai-connect

example output

Detected: Apple arm64 | Darwin

pytorch 2.5.1 (MPS accelerated)

jax 0.4.35 (metal backend)

python 3.12.4 | mypy 1.11.2

rustc 1.95.0 | clippy 0.1.95 (edition 2024)

clang++ 17.0.6 | clang-tidy 17.0.6 (c++20)

Listening on http://127.0.0.1:52341

Your code runs on your machine. We never see it. Setup takes 30 seconds.