The same animation is not the same animation in two runtimes.

iterations: 3 plays three times. repeat: 3 plays four — WAAPI, CSS and Lottie count plays, while GSAP’s repeat and anime.js’s loop count additional cycles. Copy the number across and you have added exactly one cycle, every time, in the same direction. Nothing about it reads as an off-by-one.

The engine is free and needs no account. Paste the animations — the runtime the numbers are written in, and every duration, easing and iteration count. The unit is not the same unit: CSS, WAAPI and anime.js are milliseconds, GSAP is seconds, Lottie is frames — and a Lottie duration is additionally quantised, so 250 ms is 7.5 frames at 30 fps and becomes 8, playing 16.7 ms long forever after. The end state differs, and the default is the one that snaps back: fill and animation-fill-mode both default to none, so two of the five revert the instant the animation finishes. And the easing does not map — an easing curve is a function, so the nearest equivalent has a measurable error: ease-out costs 2.4% of the travel in GSAP, bounce.out costs 24.4% in CSS, and elastic.out costs 79%, which is not a substitution at all. Every lane ships a worked example that costs nothing. Writing the report needs credits.