How CSS Keyframe Animations Work
A css keyframes generator like this one produces two connected pieces: an @keyframes block defining what changes at each percentage step of the animation, and an animation shorthand property on the target selector that ties everything together. That shorthand packs six values into one line: duration (how long one cycle takes), timing-function (the easing curve), delay (a pause before it starts), iteration-count (how many times it repeats, or infinite), direction (whether alternating cycles reverse), and fill-mode (what styles apply before the animation starts or after it ends). Getting all six right by hand, in the correct order, is exactly the kind of detail this tool exists to eliminate.
How to Use This CSS Animation Generator
This keyframe animation generator online starts with 15 built-in presets: a css fade in animation generator preset (and its fade-out counterpart), four slide directions, zoom in/out, bounce, pulse, shake, a css spin animation generator preset, ping, and flip, or choose custom to define your own keyframes. Set the CSS selector to match your actual element, then adjust Duration and Delay in seconds, Iterations (a number, or the word infinite for animations that loop forever), Easing (including a cubic-bezier option for a fully custom curve), Fill mode, and Direction to match the effect you want. Copy or download the generated css bounce animation css code (or any other preset's code), then apply the class or selector to your markup, the live preview updates immediately so you can see the result before committing to it.
Writing Custom Keyframes Without CSS Syntax
This json to css keyframes feature means you don't need to already know @keyframes syntax to define a custom animation: write {"0%":{"opacity":"0"},"100%":{"opacity":"1"}} and this tool converts it into a real, correctly-formatted @keyframes block automatically, one JSON key per percentage step, one nested object per set of CSS properties at that step. If you already know CSS and prefer to write @keyframes directly, that works too, paste raw CSS starting with @keyframes and it passes through unchanged instead of being re-parsed.
Why This Tool Always Includes a prefers-reduced-motion Block
Every animation this tool generates ships with an automatic @media (prefers-reduced-motion: reduce) block that disables the animation entirely for users who've turned on reduced-motion at the operating system level, a real accessibility setting used by people with vestibular disorders or motion sensitivity, not just a preference toggle. This isn't optional or something you need to remember to add separately, it's baked into every generated result by default, matching the same accessibility-by-default approach modern CSS frameworks increasingly build in rather than leaving as an afterthought.