Lottie in a nutshell
Lottie is an open JSON format, created at Airbnb in 2017, that describes vector animations exported from Adobe After Effects with the Bodymovin plugin. Apps render it natively at any resolution, which makes it popular for UI micro-interactions, onboarding screens and loaders. dotLottie (.lottie) is a zipped package of one or more Lottie animations plus assets.
GIF is the opposite: a rasterised, universally supported image. Converting lets you drop an animation into documentation, emails, chats, presentations or design reviews where a Lottie player isn’t available.
Quality tips
Lottie animations often run at 30 or 60 fps. GIFs above 25–30 fps add size without much visible benefit, so 25 fps is the default. Thin strokes and soft gradients are the hardest parts for GIF’s 256-colour palette — render a little larger than needed, then use Resize GIF if you need a smaller version, and the GIF compressor for size. Telegram stickers are also handled by Sticker to GIF, and SMIL/CSS animations by SVG to GIF.