Add 2-10 screenshots, select Horizontal, drag them into left-to-right order, then adjust height, spacing and background. The preview updates without a separate create button.
Prepare comparable captures
Side-by-side layouts work best when screenshots have similar visual scale. Capture the same app state or crop away unrelated browser chrome before combining. The stitcher preserves each source ratio and normalizes height.
Set the reading order
Put the earlier state on the left and the later state on the right for a before/after comparison. For several steps, arrange them in the same order as written instructions. Drag thumbnails or use accessible move controls.
Use spacing as a separator
A small gap makes boundaries clear without wasting the canvas. Choose a background that contrasts with the screenshots. Zero spacing works when the images are continuous slices of one wide interface.
Watch the total width
Horizontal output can become extremely wide. The tool calculates dimensions before rendering and reports browser canvas limits rather than attempting an unsafe export. Reduce normalized height or use fewer captures if needed.
Download what you previewed
Choose PNG when interface text must remain crisp or JPG when a smaller photo-heavy comparison is more important. The exported order, spacing and background match the automatic preview.