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Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

plain-text file

A file that holds only characters, with no hidden formatting.

A plain-text file stores nothing but a sequence of characters; source code must be plain text, which is why word processors and rich-text mode are the wrong tools for writing it.

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