Python + NumPy in the browser
This page runs real CPython — with NumPy — inside your browser via
WebAssembly (Pyodide). Every file it loads comes from this site's own
domain; there is no server-side execution and no third-party request.
Edit the code and run it.
import numpy as np
from time import perf_counter
rng = np.random.default_rng(0x5EED)
a = rng.standard_normal((256, 256))
t0 = perf_counter()
u, s, vt = np.linalg.svd(a)
dt = perf_counter() - t0
print(f"SVD of a 256x256 Gaussian matrix in {dt*1000:.0f} ms")
print(f"largest singular values: {np.round(s[:5], 3)}")
print(f"spectral norm: {s[0]:.4f}")
Runtime: Pyodide (CPython 3.14 on WASM) + NumPy, pinned and served
from /vendor/pyodide/. See the colophon.