Responsive Image Pack Generator

• Choose one static Source image. Enter 1–8 unique whole-number Variant widths separated by commas; no width may exceed the oriented source width.
• Choose Output format and JPEG / WebP quality. Set JPEG background as a six-digit hexadecimal color if using JPEG. Optional Alternative text for snippet is escaped in the HTML attribute.
• Select Generate image pack and download responsive-images.zip. Variants are sorted by width and named image-<width>w.<format>. Review manifest.json and upload the images yourself, then adapt the snippet’s relative paths to their real location.

A 64 × 32 PNG with widths 16, 32 and 64 produces 16 × 8, 32 × 16 and 64 × 32 images, with matching 16w, 32w and 64w srcset descriptors.

• One input up to 20 MiB, 24 million source pixels and 16,384 pixels per side. At most 8 variants, 48 million total output pixels, 20 MiB per encoded variant and 100 MiB ZIP; task limit 60 seconds.
• Only static PNG, JPEG and WebP are accepted; animated input is rejected. Widths must be unique and at least one pixel. No upscaling. JPEG / WebP quality is 1–100; PNG ignores quality. Alternative text is at most 300 UTF-16 code units without controls or invalid Unicode.
• JPEG flattens transparency onto the selected background; PNG and WebP retain supported alpha. Browser color decoding and lossy JPEG/WebP encoding can change pixels. Source descriptive metadata is not copied. The downloaded snippet uses relative filenames; it does not host files or supply site layout rules.
• Cancellation discards unfinished output. A new task may wait for the current native image operation to finish.