# Lottie Inspector & Compactor

> Inspect Lottie data and remove JSON whitespace safely. Inspect Lottie dimensions, timing, layers, keyframes, expressions and asset references. Minify JSON without changing rendering fields, optionally remove root metadata, and open compatible shape animations in Flipline Motion Desk.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://fliplinelottieinspector.usefulweb.site/ (interactive tool at https://fliplinelottieinspector.usefulweb.site/tool)
- JSON API: POST https://fliplinelottieinspector.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://fliplinelottieinspector.usefulweb.site/api/v1/tool)
- OpenAPI: https://fliplinelottieinspector.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://fliplinelottieinspector.usefulweb.site/mcp - tool `flipline_lottie_inspector`

## Inputs
- json (textarea): Lottie JSON
- removeMetadata (boolean): Remove root metadata

## Method
- Parse data-only Lottie JSON with a 2 MB UTF-8 budget, a depth limit of 40 and a 160,000-value budget. Dimensions, timing and finite numbers are checked before inspection. Expressions and references are counted without execution or network requests.
- Compaction serializes the parsed document without indentation. Every field is retained unless root metadata removal is explicitly selected, which removes only the top-level meta field. Before and after sizes are UTF-8 bytes. No geometry, colors, transforms, expressions or keyframes are optimized.
- Editor compatibility checks a strict subset: 2D shape layers with solid static fills, strokes and paths, static anchors and animated position, scale, rotation and opacity. Unsupported assets, text, effects, masks, blends, parenting and spatial paths are reported. Compatible transforms are sampled at each composition frame; subframe interpolation can differ.
- Compatible imports allow 24 layers, 360 frames, 60 FPS, 60 seconds, a 2-megapixel stage and 4096 path points. A project download and editor link are returned only when the entire file fits this subset. General inspection and compaction can still be useful for unsupported files.

## Limits
- Does not render arbitrary Lottie, evaluate expressions, fetch assets or guarantee player compatibility. Compaction removes whitespace; it does not reduce geometry or keyframes.