Build a CSS keyframe animation with the timing function held to what the specification allows: named, cubic-bezier and steps easings, a preview built from the same declarations as the copied CSS, and every problem the browser would refuse named before you paste it
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Design a CSS button and see every state measured against WCAG on the page colour you name: resting, hover, active, focus and disabled, plus the focus ring and the border.
Generate fake data that is the thing it is labelled: card numbers with a real Luhn check digit, IBANs that pass ISO 7064 MOD 97-10, UUID v4 and v7 per RFC 9562, reserved e-mail and IP ranges, a seed so the same data comes back, and JSON, NDJSON, CSV or SQL output
Build a clip-path from polygons, circles, ellipses and rounded insets, with the fill rule exposed and the value checked before it is shown
Build a CSS @keyframes animation visually, with the timing function held to what the specification allows, and everything the browser would refuse named before you paste it.
The CSS Animation Generator builds a `@keyframes` block and a matching `.animated-element` rule, and the same function builds both of those and the live preview, so the box on screen and the code beside it cannot describe different animations. Eleven presets load their own keyframes with a tuned duration and timing function: Fade In, Slide Up, Bounce, Pulse, Shake, Spin, Flip and Glow, plus three that exercise the parts most generators leave out, Typewriter (24 steps, jump-end), Sprite Walk (8 steps, jump-none) and Overshoot (a cubic-bezier whose y coordinates leave 0 to 1 on purpose).
The timing function is the part a generator has to get right, because CSS Easing Functions Level 1 section 3.1 requires both x coordinates of a `cubic-bezier()` to lie in 0 to 1, and a value outside that makes the timing function invalid, which invalidates the whole `animation` shorthand, which means the element simply never moves. This tool holds x1 and x2 inside that range as you type and leaves y free, since an unbounded y is exactly how an overshoot or elastic ease is written. It also offers the step family, `steps(n, jump-start | jump-end | jump-none | jump-both)`, and states how many distinct states each combination produces, which is the number that matters when you are stepping through a sprite sheet.
Every value the tool can be given, from a control or from a shared URL, is range checked before it reaches the CSS: a name that is not a CSS identifier is rewritten and the rewriting is shown, an iteration count that is negative or not a number falls back, and a direction or fill mode that does not exist falls back. Zero is accepted everywhere it is legal, including a zero duration and zero iterations. Anything the browser will refuse, and anything it will accept but do something surprising with, is listed under the preview with the rule it breaks: duplicate keyframe offsets, where the later one wins; a property set at some keyframes and not others, where the browser interpolates rather than holding the value; and a missing 0% or 100% keyframe, where the browser falls back to the element's own computed style. Pause sets `animation-play-state: paused`, which holds the current frame, rather than removing the animation.
Bounce is a 1s cubic-bezier animation with six keyframes moving translateY from 0 to -30px at 20%, back to 0 at 40%, to -15px at 60%, and settling at 0 from 80% to 100%, which is a damped double hop.
Typewriter animates width from 0 to 240px under steps(24, jump-end), so the text is revealed in 24 discrete jumps rather than slid smoothly. A named easing cannot express this at all.
Design custom loading animations without pulling in a library.
Create entrance animations for elements as they come into view.
Build subtle hover and focus animations that make UI elements feel responsive.
Animating transform and opacity is handled by the compositor and performs well at any size. Animating width, height or margin makes the browser redo layout on every frame, which is why those three carry a note in the property list.
Yes. Use animation-delay to stagger them, or list several animation names on one element separated by commas. This tool writes one animation at a time.
Almost always one invalid component in the animation shorthand. CSS applies a shorthand as a whole, so a cubic-bezier with an x outside 0 to 1, an iteration count that is not a number, or a name that is not a valid identifier throws away the entire declaration rather than just that part. This tool checks each one and says so under the preview, which is why it also holds the Bezier x values in range for you.
How many states you get. Plain steps(4) means jump-end and gives 5 states including the start; jump-none holds both ends and gives exactly 4. For a sprite sheet with 4 frames, jump-none is the one that shows each frame once.
This runs as client-side JavaScript. Keys, tokens, payloads, and other inputs never leave your device.