RegexLearn

Regular expressions look like line noise until someone walks you through them. RegexLearn does exactly that: it turns regex from a black art into a skill you can pick up in an afternoon, one small interactive step at a time.

What it does

• Step-by-step lessons: each step introduces one idea and lets you try it right away, from simple matches to lookarounds.
• Two courses: Regex 101 for the fundamentals and Regex for SEO for practical, search-focused patterns.
• Cheatsheet: the whole syntax on one page, for when you just need a reminder.
• Playground: a private, browser-based sandbox to write and test your own patterns.
• Keyboard friendly: move through lessons without touching the mouse.

Open source, in 21 languages

RegexLearn is free and fully open source, and it has grown far beyond what I expected: more than 4,000 stars on GitHub and lessons translated by the community into 21 languages, from Turkish and Spanish to Japanese and Arabic. Most of those translations came from contributors who learned regex on the site and wanted to make it available in their own language.