How to reduce Lottie file size (without visual loss)
Heavy Lottie files hurt load times and Lighthouse scores, and most of the weight is invisible: excessive numeric precision and authoring metadata. Here's what actually shrinks a file, in order of effort.
1. Reduce numeric precision (the big, safe win)
Keyframe and path arrays store coordinates like 245.33333333333334 — precision no screen can show. Rounding to 2–3 decimals is visually lossless and often trims a meaningful slice of the file. The optimizer here does this conservatively and shows exact before/after sizes.
2. Strip authoring metadata
After Effects match-names ("mn") and layer names ("nm") never affect rendering in normal playback. Removing match-names is always safe; the optimizer drops them by default.
3. Package as dotLottie
ZIP compression inside a .lottie container typically saves another 30–50% on top — Lottie JSON compresses extremely well. Optimize first, then package, for the smallest shippable file.
4. Fix it in the design
The biggest offenders are structural: embedded raster images, huge path counts from auto-traced artwork, and hidden layers left in the comp. If a file is megabytes after optimization, the wins left are in After Effects, not in any converter.
