Click tokens to assemble a regular expression and watch it run against your own text. Nothing leaves the browser: the pattern is compiled with the built-in engine, every match is highlighted, and a broken pattern explains itself instead of failing.
Insert a token
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Result
Matches in sample text
Convert numbers between bases with a live bit view.
Convert colours three ways with a live preview.
Strong random passwords from crypto.getRandomValues.
Live Markdown preview rendered in the browser.
Add a million numbers the naive way and against Kahan compensation, and watch the error grow or stay flat.
Distances and coordination sequences on a lattice grid, for crystal and network geometry.
The logistic map from r 2.7 to 4.0, with the bifurcation diagram drawn live as you drag the growth rate.
Factor any integer, build a smallest-prime-factor sieve, and see the primes light up in a density grid.
