Join multiple images vertically or horizontally into one long seamless scrolling image.
Long Image Joiner converts several separate image files into one continuous strip, with the images stacked from top to bottom or placed from left to right. It performs concatenation, so every source becomes a consecutive section rather than being blended like part of a panorama. The main surprise is that "seamless" describes one uninterrupted output image, not automatic removal of repeated screenshot areas or correction of mismatched edges. Crop unwanted overlap and check source dimensions before joining.
A concrete input and expected output from the current implementation.
Input
Choose vertical joining. Add a 4 x 2 pixel PNG filled with red (#ff0000), followed by a 4 x 2 pixel PNG filled with blue (#0000ff).
Expected output
One 4 x 4 pixel image: rows 1 and 2 are red, and rows 3 and 4 are blue.
The common width remains 4 pixels. Vertical joining adds the two 2-pixel heights, producing a total height of 4 pixels.
Vertical mode places each complete image beneath the preceding image; horizontal mode places each one beside the preceding image. When vertical inputs have equal widths, the output keeps that width and adds their heights. When horizontal inputs have equal heights, it keeps that height and adds their widths. This is end-to-end concatenation, not content-aware panorama stitching.
The source images are handled entirely in the browser and are not uploaded. The combined result is one flattened image rather than a layered document with independently movable sections. Large source files or an exceptionally long result can consume substantial browser memory, so practical capacity depends on the device and the image dimensions the browser can create.
No. Long Image Joiner places complete images consecutively; it does not detect shared pixels, match landmarks, or remove duplicated overlap like a panorama stitcher. If two screenshots repeat the same header or lines of text, crop one copy of that region before joining so the transition reads correctly.
It can make a single left-to-right row by using horizontal joining. That works for comparisons or ordered frames with compatible heights. It is not a general contact-sheet layout tool: a multi-row grid, captions, numbered cells, margins, and independently positioned thumbnails require a separate layout or image-editing tool.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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