Scroll-Driven Animation Builder — Visual CSS scroll() Animation Tool

Scroll-Driven Animation Builder is a free, browser-based tool that lets you configure CSS scroll-driven animations visually — choose a property to animate, set animation-range start and end, pick an easing function, and watch the result live in a scrollable preview panel. Copy the generated CSS and paste it into your project. No JavaScript, no account, no install.

The Problem

CSS scroll-driven animations (landed in Chrome 115, Edge 115) let you link any CSS animation's progress to a scroll container's position. But the syntax has several moving parts:

@keyframes fade-in {
  from { opacity: 0; }
  to   { opacity: 1; }
}
 
.element {
  animation: fade-in linear both;
  animation-timeline: scroll(y);
  animation-range: cover 20% cover 80%;
}

The animation-range property alone accepts combinations of five keywords (cover, contain, entry, exit, normal) plus percentages — and the result is non-obvious until you see it playing. Without a visual tool, the workflow is: write code → reload browser → adjust → reload again.

Designers and developers who are new to scroll-driven animations spend more time fighting syntax than building experiences.

How It Works

1. Choose What to Animate

Pick from six ready-made animation properties:

| Property | Effect | |----------|--------| | Opacity | Fade in or out | | Scale (transform) | Grow or shrink | | Translate Y | Slide up or down | | Translate X | Slide left or right | | Rotate | Spin | | Blur (filter) | Sharpen from blur |

Each property pre-fills sensible from and to defaults. You can override them to any value — negative translate values, sub-1 opacity, full rotations.

2. Set animation-range

Two dropdowns let you choose a range keyword for the animation start and end, each paired with a percentage slider:

• cover — relative to the element covering the scroller viewport edge
• contain — relative to the element fitting inside the viewport
• entry — relative to the element entering the scroller
• exit — relative to the element leaving the scroller
• normal — default CSS behaviour (no range restriction)

The live preview updates immediately as you drag the sliders or change keywords.

3. Pick an Easing Function

Select from six easing options — linear, ease-in, ease-out, ease-in-out, and two custom cubic-bezier curves. The choice changes how the animation accelerates across the scroll range.

4. Choose Scroll Axis

The scroll() function accepts an axis argument — y (default), x, block, or inline. Toggle between axes to match your layout.

5. Live Scroll Preview

The preview panel contains a scrollable box. Inside it, the animated element plays the configured animation as you scroll — no page reload, no inspecting code. The animation updates within milliseconds of any control change because the tool injects a scoped <style> tag into the document.

6. Copy the CSS

The generated CSS panel shows the full output including the @keyframes block and the element rule. One click copies it to clipboard.

Key Features

• Six animation properties — opacity, scale, translate Y/X, rotate, blur
• animation-range controls — keyword selector + percentage slider for start and end
• Live scroll preview — scrollable box shows the animation playing in real time
• Six easing functions — including linear and common cubic-bezier curves
• Scroll axis selector — y, x, block, inline
• One-click CSS copy — production-ready @keyframes + animation rule
• Custom animation name — name the keyframes anything for your project
• Reset button — return to sensible defaults in one click
• Zero JavaScript in output — generated code is pure CSS
• No signup required — open the URL, start building

Technical Implementation

Core Technologies

• Next.js 16 with App Router
• TypeScript in strict mode
• Tailwind CSS v4 with OKLCH color tokens
• React 19 — useId, useCallback, useEffect, useRef
• Framer Motion for page entry animations
• shadcn/ui components (Button, Toaster)
• Sonner for toast notifications
• Google Analytics 4 for usage tracking

Architecture

The tool uses a scoped style injection approach:

1. Each tool instance gets a unique ID via useId()
2. A <style> element is created and appended to document.head
3. The style content is regenerated and updated via useEffect whenever any config value changes
4. The animated element receives a class derived from the unique ID — isolation prevents conflicts when multiple instances exist

The scrollable preview container uses overflow-y: scroll with a fixed height of 320px. The animation-timeline: scroll() function targets the nearest scrolling ancestor, so the animation plays relative to the preview box rather than the page — enabling the live preview without full-page scroll interference.

CSS generation is pure string interpolation — no external CSS-in-JS libraries. The output is always valid, copy-pasteable CSS.

Type Safety

All configuration options are typed with TypeScript union types:

• AnimationProperty — the six animatable property keys
• RangeKeyword — the five animation-range keywords
• EasingFn — the six supported timing functions

Default values are typed and derived from the constants — no magic strings scattered through the component.

Use Cases

Entrance Animations for Sections

A common pattern: sections that fade in and slide up as the user scrolls to them. Previously this required IntersectionObserver + JavaScript class toggling. With scroll-driven animations:

@keyframes section-enter {
  from { opacity: 0; transform: translateY(40px); }
  to   { opacity: 1; transform: translateY(0); }
}
 
.section {
  animation: section-enter ease-out both;
  animation-timeline: scroll(y);
  animation-range: entry 0% entry 100%;
}

The builder lets you prototype this in seconds — adjust the range to control how much of the entry phase triggers the animation.

Parallax Effects

Use Translate Y with a large range to create subtle parallax depth. Set from to a negative value and to to a positive value — the element appears to move at a different rate from the scroll.

Progress Indicators

Animate scaleX from 0 to 1 on a fixed progress bar element with animation-timeline: scroll(y) targeting the document scroller (using :root as the container). The builder generates the keyframes; you adapt the selector for your use case.

Scroll-Based Colour Transitions

Configure opacity from 1 to 0 to make decorative elements fade as the user scrolls past them. Combine with CSS background-color transitions in a multi-keyframe block to create colour-shifting headers.

Learning animation-range

The most underappreciated use: learning. Understanding which percentage value of which keyword triggers the animation for a specific layout is hard to reason about in the abstract. The live preview makes the relationship concrete — change a number, see the effect, build the intuition.

Browser Support

Scroll-driven animations require Chrome 115+, Edge 115+, or Opera. Firefox support is available behind layout.css.scroll-driven-animations.enabled in about:config as of Firefox 110; native support is expected soon.

For production use, apply a @supports guard:

@supports (animation-timeline: scroll()) {
  .element {
    animation: my-anim linear both;
    animation-timeline: scroll(y);
    animation-range: cover 0% cover 100%;
  }
}

Without the guard, browsers that do not support animation-timeline simply ignore the rule — the element renders in its final to state.

Why Scroll-Driven Animation Builder?

vs. Manual CSS + Browser DevTools

• Instant preview without saving — controls update the animation live; no file save, no reload
• Keyword exploration — try all five range keywords without memorising their behaviour first
• Ready output — no need to write the @keyframes block or remember the both fill mode

vs. JavaScript Solutions (GSAP ScrollTrigger, etc.)

• No runtime dependency — zero JavaScript in the generated output
• Simpler mental model — one CSS property controls the timeline, not an event-driven animation library
• Performance — scroll-driven animations run on the compositor thread without main-thread JavaScript

vs. Other CSS Generators

• Scroll-specific controls — animation-range keyword/percentage pairs, not just animation shorthand
• Live scroll preview — not a static visual; you actually scroll to see the result
• Axis control — the scroll() axis argument is rarely surfaced in tooling

Try it now: scroll-driven-animation-builder.tools.jagodana.com