lottie-optimize-babashka

Babashka (Clojure) CLI tool that optimizes Lottie JSON animation files by compressing embedded images, truncating float precision, stripping editor metadata, and minifying output.

Install

The install script checks that all requirements are present before downloading.

curl -fsSL https://raw.githubusercontent.com/ampersanda/lottie-optimize-babashka/main/install.sh | bash

Requirements

The following must be installed before running the install script:

• Babashka (bb)
• ImageMagick (magick)
• libwebp (cwebp) -- optional but recommended

brew install borkdude/brew/babashka imagemagick webp

The script installs optimize-lottie to ~/.local/bin. Make sure it is in your PATH:

export PATH="${HOME}/.local/bin:${PATH}"

Uninstall

rm ~/.local/bin/optimize-lottie

Usage

If installed via the install script:

# Basic (images downscaled to canvas size, WebP q80)
optimize-lottie -i animation.json

# Lossless (pixel-perfect, no quality loss)
optimize-lottie -i animation.json -o output.json --lossless

# Custom quality and max image size
optimize-lottie -i animation.json -q 95 -s 512

# Reduce framerate
optimize-lottie -i animation.json --fps 30

Or run directly with Babashka:

bb optimize-lottie.bb -i animation.json
bb optimize-lottie.bb -i animation.json -o output.json --lossless
bb optimize-lottie.bb -i animation.json -q 95 -s 512
bb optimize-lottie.bb -i animation.json --fps 30

Options

Flag	Description	Default
-i, --input	Input Lottie JSON file	required
-o, --output	Output file path	<input>.optimized.json
-s, --max-image-size	Max image dimension (px)	canvas size
-q, --webp-quality	WebP quality 0-100	80
-p, --precision	Float decimal places	3
-f, --fps	Target framerate	keep original
-l, --lossless	Lossless WebP	false

Examples

Full-screen looping confetti animation examples located in example/.

Warning

All examples symlink to animations/confetti.json. Changes to that file are reflected immediately across all example projects.

iOS

Uses SwiftUI + lottie-ios (SPM).

cd example/ios/LottieExample
open LottieExample.xcodeproj

Xcode resolves the Lottie SPM dependency automatically. Select a simulator or device and run.

Android

Uses Jetpack Compose + lottie-compose.

cd example/android
./gradlew installDebug
adb shell am start -n com.example.lottieexample/.MainActivity

Or open the example/android folder in Android Studio.

Flutter

Uses lottie with Very Good Analysis. Tested on iOS, Android, and macOS.

cd example/flutter
flutter pub get
flutter run

ClojureDart

Uses ClojureDart with lottie.

cd example/clojuredart
clj -M:cljd flutter

How it works

1. Image compression - Downscales embedded PNG images to fit the animation canvas, converts to WebP (or keeps PNG if smaller), picks the smallest result
2. Layer transform adjustment - Updates asset dimensions to match resized pixels, then compensates image layers by scaling anchor points and scale transforms so rendering stays correct on both iOS and Android
3. Float truncation - Reduces excessive decimal places in keyframe data
4. Metadata removal - Strips After Effects editor-only properties (mn)
5. JSON minification - Removes whitespace

Typical results: ~80-94% file size reduction depending on quality settings.