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Common Mistakes and Confusing Words in English
Both leaped and leapt are the past form of the verb to leap. The difference between them is purely about what English you want to learn, British English (BrE) or American English (AmE).
In the UK we say leapt. To leap - I leapt - I have leapt - I am leaping.
In the US they have made the verb "to leap" into a regular verb (they do that a lot) so they add -ed and say leaped.
!Note - Lept is wrong, but it does show you how Brits pronounce leapt.