Animation joiner

• Choose two to four animation files in the required output order.
• Choose a sequential or spatial layout and hold/repeat behavior for shorter animations.
• Choose output format and total plays, compose, preview and download the animation and timing manifest.

Place two animations side by side, hold the shorter final frame, and export a three-play APNG.

• Animated GIF, APNG and WebP inputs are fully composited with their blend/disposal rules before editing. APNG support is non-interlaced 1–8-bit grayscale/palette or eight-bit RGB/RGBA; re-save 16-bit and Adam7 files first. Animated WebP requires a browser with ImageDecoder support.
• At most 20 MiB total input, four files, 4096 pixels per side, four megapixels per frame, 20 million decoded input canvas pixels, 20 million output canvas pixels and 300 output frames. Output is at most 40 MiB; one cycle is at most five minutes. The cancellable worker has a 120-second overall deadline.
• One source cycle is used per input. Cumulative source boundaries round to milliseconds; zero stored delays become 100 ms. GIF output rounds cumulative boundaries to 10 ms and rejects any collapsed visible interval. Very short delays may still be clamped by viewers.
• APNG retains composited eight-bit RGBA samples; GIF thresholds alpha at 128 and reduces each frame to at most 255 opaque colors; WebP RGB is lossy at every quality level while alpha is retained. Metadata and source profiles are not copied. Downloaded timing JSON explains output delays and loop semantics.
• Join two to four existing animations in selected file order. Sequence plays one cycle of each; horizontal, vertical and two-column-grid layouts play simultaneously for the longest input cycle.
• Original pixel sizes are retained, centered with transparent padding. Simultaneous layouts either hold each shorter input’s last frame or repeat its cycle; source loop flags do not expand processing duration. Output plays are explicit (zero means forever); no least-common-multiple expansion is attempted.