CSS animations are free, fast, and native. Lottie handles complexity that CSS can't. This guide helps you choose the right tool for every motion design scenario.
Lottie: Overkill (8 KB + player)
CSS: ~0 KB (2 lines CSS)
Verdict: CSS
Lottie: 4 KB JSON
CSS: ~0 KB (CSS keyframes)
Verdict: CSS
Lottie: 12 KB JSON
CSS: ~0 KB (CSS + JS triggers)
Verdict: Depends on complexity
Lottie: 45 KB JSON
CSS: Impractical to replicate
Verdict: Lottie
Lottie: 80 KB JSON
CSS: Not feasible in CSS
Verdict: Lottie
Lottie: 15 KB + scroll library
CSS: ~0 KB + Intersection Observer
Verdict: CSS for simple, Lottie for complex
The most performant production apps combine both approaches. Use CSS for UI state transitions (button hovers, page fades, skeleton loading) and Lottie for rich, illustrative motion (onboarding flows, success celebrations, empty states). This gives you zero-dependency performance where it matters and design-fidelity animation where it shines.