Merge images into one

Side by side is the before-and-after layout: an edited photo next to the original, or two screenshots of a bug so whoever reads the ticket sees both states at once. Stacked puts images in one column, which suits a long receipt photographed in three parts or a two-page form shot page by page.

Grid fills 2 to 5 columns, left to right, top to bottom. It helps when a marketplace listing accepts one image and you have four product shots. Empty cells in a short last row take the background color. Reorder with the arrows on each row, or drag it.

Match sizes is on by default. Side by side, every image gets the same height; stacked, the same width; in a grid, each image is fitted into an equal cell. Scale to sets the reference: The largest image keeps the big photo at full resolution and enlarges the rest, which can look soft; The smallest image never enlarges and gives a lighter file.

With Match sizes off, every picture keeps its pixel size, Alignment decides whether shorter images sit at the top, middle or bottom (left, center or right in a column), and leftover space takes the background. Spacing and outer padding each go from 0 to 200 px; the background can be any color or transparent.

If any input has transparent pixels, or the background is transparent, PNG is preselected to keep the alpha channel. Otherwise JPG at quality 92 is preselected, because PNG is far larger for photos. Two 1200 × 800 JPGs of 224,092 bytes each, merged side by side with a 10 px gap, gave a 449,203-byte JPG, a 354,910-byte WebP at quality 92 and a 1,922,490-byte PNG.

JPG cannot store transparency, so transparent areas turn white and the settings panel says so. The file is saved as merged-image.jpg, .png or .webp. EXIF data is not copied, but its orientation is applied first, so portrait phone photos stand upright.

Browsers refuse canvases above a certain size, and some browsers on iPhone limit the total pixel count more tightly. So, to be safe, the output is kept to 16,384 px per side and 16,777,216 pixels in total; a larger layout is scaled down as a whole, spacing included, and a note shows the percentage. Two 4032 × 3024 phone photos side by side would be 8064 × 3024, so they come out at 6688 × 2508, 82% of full size. Three portrait receipt photos stacked come out at 2048 × 8192.

Each file can be up to 50 MB. The preview uses small copies; full-size images are decoded one at a time when you press Download merged image. Eight 2400 × 1600 PNGs side by side (scaled to 14188 × 1182) took 0.7 to 0.9 seconds in Chromium on a Mac. Nothing is uploaded. This is a merge tool, not a collage designer: no free placement, text or frames.