The Lottie optimizer takes Lottie JSON animation files and removes editor-only fields while narrowing floating-point precision to 3 decimal places, shrinking the file without affecting playback. Multiple files can be uploaded at once; all processing happens locally in the browser with no server upload.
How Much File Size Can You Expect to Lose
Compression depends on how much redundant data the original file contains. Files exported directly from After Effects or LottieFiles typically contain layer names (nm), match names (mn), hidden flags (hd), and index fields (ix) that serve no purpose during playback. Removing them puts the reduction in the 20–50% range for typical exports, and above 60% for complex project files. The tool displays exact before/after sizes and a percentage change for each file:
125.48 KB → 67.92 KB (-46%)
What the Optimizer Actually Removes
Deleted fields: layer name (nm), match name (mn), hidden marker (hd), index (ix), and any empty effects arrays (ef: []).
Number handling: floating-point values are rounded to 3 significant decimal places; integers are preserved exactly. This trims JSON text length without degrading the visual accuracy of animation curves.
Batch Processing and Download
Upload multiple .json files in one session. Each file gets its own animated preview and size comparison panel. Download buttons are per-file; the output filename is prefixed with optimized-.
When to Optimize and When to Skip
Good candidates for optimization
- Files exported directly from an AE plugin (usually packed with debug fields)
- Animations served over CDN or in mobile first-screen loading
- Any file where you've finished editing and need a production copy
Skip optimization if
- The file still needs editing in AE or LottieFiles
- The file is already very small (under 5 KB) — gains will be negligible