Build CSS keyframe animations visually with 12 presets and a custom keyframe editor. Supports timing functions, iteration, direction, fill mode — with live preview and replay. Free online animation builder.
CSS Animation Generator is a free online tool that lets you visually build CSS keyframe animations with a real-time preview. Choose from 12 ready-made presets including fade, slide, bounce, pulse, shake, rotate, zoom, flip, and swing — or build your own custom animations by defining keyframes, timing functions, duration, delay, iteration count, direction, and fill mode. The tool generates clean, copy-ready CSS code with both the @keyframes block and the animation shorthand property.
Use the CSS Animation Generator when you need to create entrance animations for page elements, loading spinners, attention-grabbing hover effects, micro-interactions for buttons and cards, or any CSS-only animation that runs without JavaScript. It is especially useful when prototyping animation ideas — you can adjust timing, easing, and keyframe properties in real time and see the result instantly before writing a single line of code in your project.
Front-end developers commonly use CSS Animation Generator to create page load entrance animations (fade in, slide up), build infinite loading spinners and progress indicators, design attention-grabbing call-to-action button animations, prototype scroll-triggered animation sequences, create tooltip or dropdown appear/disappear transitions, and build notification badge pulse effects. The preset library covers the most common animation patterns used in modern web design.
Essential terms and definitions related to CSS Animation Generator.
A CSS at-rule that defines the stages of an animation by specifying styles at various points during the animation sequence. Each keyframe is specified as a percentage (0% to 100%) or using the "from" (0%) and "to" (100%) keywords. The browser interpolates property values between keyframes to create smooth transitions.
The CSS animation property is a shorthand for setting all animation sub-properties in one declaration: animation: name duration timing-function delay iteration-count direction fill-mode play-state. For example: animation: fadeIn 0.5s ease-out 0s 1 normal forwards running. Only name and duration are required; the rest have default values.
A mathematical function that defines the rate of change of an animation over time. Linear easing produces constant-speed motion. Ease functions (ease, ease-in, ease-out, ease-in-out) produce acceleration and deceleration curves. Custom easing can be defined with cubic-bezier(x1, y1, x2, y2) for precise control over the animation curve.
A dedicated browser thread that handles rendering of GPU-accelerated properties (transform, opacity) independently of the main thread. Animations running on the compositor thread are not blocked by JavaScript execution, layout calculations, or garbage collection on the main thread — resulting in smooth 60fps animation even when the main thread is busy.
The animation-fill-mode property that defines what styles are applied to the element outside of the animation's active duration. "forwards" applies the last keyframe styles after the animation ends. "backwards" applies the first keyframe styles during the animation-delay period. "both" applies both behaviors. "none" (default) removes all animation styles when the animation is not active.
CSS transitions animate between two states (usually triggered by :hover or class changes) and require a trigger event. CSS animations use @keyframes to define multi-step sequences that can run automatically on load, loop infinitely, and define complex motion paths. Use transitions for simple hover/state changes; use animations for entrance effects, loading spinners, and continuous motion.
ease (default): slow start, fast middle, slow end — good for most UI animations. linear: constant speed — good for spinners and continuous motion. ease-in: slow start, fast end — good for exit animations (elements leaving the screen). ease-out: fast start, slow end — good for entrance animations (elements entering the screen). ease-in-out: slow start and end — good for back-and-forth or looping animations.
fill-mode controls what styles apply before and after the animation runs. "none" (default): element returns to its original styles after the animation ends. "forwards": element retains the final keyframe styles after completion. "backwards": element applies the first keyframe styles during the delay period before the animation starts. "both": combines forwards and backwards behavior. Most entrance animations should use "forwards" to keep the final state.
Set iteration-count to "infinite" and ensure your first and last keyframes have identical property values. For example, rotate: 0% { transform: rotate(0deg) } to 100% { transform: rotate(360deg) } loops smoothly because 360deg = 0deg. For bounce effects, use "alternate" direction so the animation reverses each cycle. Avoid abrupt property jumps between 100% and 0% keyframes.
Yes. CSS supports multiple animations on a single element by comma-separating animation values: animation: fadeIn 0.5s ease forwards, slideUp 0.5s ease-out forwards. Each animation can have independent timing, delay, and keyframes. Be careful with conflicting properties — if two animations modify the same property (e.g., transform), the last one in the list wins.
Animations on transform and opacity properties are GPU-accelerated in all modern browsers and run on the compositor thread — they do not trigger layout or paint and are extremely performant. Animating layout-triggering properties like width, height, margin, or top causes layout recalculations (reflow) and should be avoided. Use transform: translateX() instead of left, and transform: scale() instead of width for smooth 60fps animations.
Common errors developers encounter and how to resolve them.
Animation not playing: element does not move or change Check that the @keyframes name matches the animation property name exactly (case-sensitive). Verify that the element has the animation property applied (not just the @keyframes definition). If using fill-mode: forwards with opacity: 0 at 0%, the element may appear invisible before the animation starts — add a delay or use fill-mode: both. Also check for CSS specificity conflicts that might override the animation property.
Animation jittering or not smooth at 60fps Only animate transform and opacity — these are GPU-accelerated and composited on a separate thread. Animating width, height, margin, padding, top, left, or box-shadow triggers expensive layout recalculations. Replace left with translateX(), top with translateY(), and width/height changes with scale(). Add will-change: transform to the element as a hint to the browser to prepare for animation.
Animation plays once but does not restart on class toggle Browsers do not restart an animation when the same animation name is re-applied. To replay, remove the animation, force a reflow, then re-add it: element.style.animation = "none"; void element.offsetHeight; element.style.animation = "". Alternatively, use a unique animation name each time, or toggle a CSS class with a requestAnimationFrame gap.
Keyframe properties overriding each other in multi-step animations In @keyframes, properties that are not explicitly set at a keyframe are interpolated from the nearest keyframes that do define them. If you set opacity at 0% and 100% but not at 50%, the 50% value will be interpolated (0.5). If you need a property to hold a value for a range, set it explicitly at both the start and end of that range. Example: 0% { opacity: 1 } 40% { opacity: 1 } 50% { opacity: 0 } keeps opacity at 1 from 0% to 40%.