Long Image Joiner

Join multiple images vertically or horizontally into one long seamless scrolling image.

Tested tool guide Tested browser tools Checked August 16, 2026

What Long Image Joiner does, with a checked example

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.

Worked example

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.

How the result is produced

Join direction

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.

Single local result

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.

Good uses

Combine consecutive phone screenshots into one top-to-bottom record of a conversation, article, settings screen, or checkout flow.
Place two design renders, charts, or before-and-after images into one left-to-right comparison strip without constructing a larger document.
Assemble scanned panels, map sections, comic pages, or instruction steps into a continuous image that readers can scroll through in sequence.

Limits and checks

For a vertical join, differing source widths create a cross-axis mismatch; for a horizontal join, differing heights do the same. Inspect the finished image for alignment, scaling, cropping, or empty side areas rather than assuming the smaller images will be handled in a particular way.
Overlapping screenshots remain overlapping. Repeated headers, navigation bars, timestamps, or lines of text will appear twice unless those regions are removed before the images are joined.
A very long image may be displayed at a reduced scale by browsers, document viewers, or messaging services. Some destinations may also recompress it or impose their own dimension limits, so verify the delivered copy rather than judging only the locally generated result.

Common questions

Does it automatically stitch overlapping screenshots?

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.

Can it make a horizontal contact sheet?

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.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.