Sprite Atlas Packer

How to use Sprite Atlas Packer

Pack original raster sprites into atlas PNG pages with a real CSS/JSON coordinate manifest. A deterministic shelf packer reserves padding, plans nonoverlapping placements before decoding, and draws original-size pixels sequentially. A ZIP contains each atlas, escaped JSON source names and fixed generated CSS classes.

1. Provide ordered raster files, atlas page width, atlas page height, sprite padding.
2. Choose the supported mode and run the tool. Review its assumptions and any reported errors.
3. Copy the result or download a separate output; reset to clear the current form.

Good to know

• Static PNG, baseline JPEG or simple VP8/VP8L WebP; each≤8MiB,4,000,000 pixels and4,096px per side. Progressive JPEG, VP8X/animated WebP, APNG and compressed PNG profiles/text or PNG EXIF are excluded. Full container structure is checked before native decoding; this is not a complete codec validator. Browser decoding/export can still reject a file or change color profiles. Output is a fresh PNG without original container metadata.
• 100 files/20MiB,4 pages,8,388,608 combined source+atlas pixels. Each sprite and its padding must fit one page. No rescaling, rotation or optimal packing claim.
• Oriented dimensions must match header dimensions; normalize rotated EXIF inputs first. Generated CSS uses fixed sprite-1 names rather than input-derived selectors.
• Inputs are processed on this device and are not automatically saved or uploaded.