Merge Images FREE | Combine Photos Side by Side or Stacked Online

Merge two or more images by placing them side by side (horizontal) or stacked vertically. Control the gap and background colour between images. Add up to 10 images. Preview and download the merged result as JPG, PNG, or WebP. Runs locally in your browser.

Private — No Upload

Horizontal or Vertical

Up to 10 Images

Free Forever

Merge Images Tool

Drop images or click — up to 10 files

Frequently Asked Questions

In horizontal layout, all images are aligned to the tallest image height and placed side by side at their original widths. Shorter images are vertically centred. In vertical layout, images are aligned to the widest image width and stacked at their original heights, horizontally centred. The images are not resized — only positioned. For a clean merge, ensure all images have the same height (for horizontal) or width (for vertical) before merging, using the Resize tool.

The gap adds a solid-colour space between the images. A gap of 0 places images touching edge-to-edge. A gap of 10-20px creates a thin separator line in the background colour. A gap of 50-80px creates a wide mat border between images, similar to a multi-panel gallery print. The gap background colour is the same as the main background colour set in the colour picker.

This tool supports merging up to 10 images in a single operation. For more images, merge them in two batches (e.g. 5 images each) and then merge the two resulting images. The total output file size increases with each additional image, and very large merges may be slow on low-memory devices.

No quality is lost in the merge process — each source image is drawn to the canvas at its original pixel dimensions with no rescaling. JPEG output applies the standard 0.92 quality level to the merged canvas; PNG output is lossless. The output quality is limited by the quality of the input images, not by the merge process itself.

Load the before image first, then the after image. Select horizontal layout with a gap of 2-5px in a contrasting colour (such as white or black). The result is a standard before-and-after comparison format. For larger files, you may want to resize both images to the same height first using the Resize tool before merging.

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Free Image Merge Tool Online — Combine Photos Side by Side or Stacked Vertically

Combining multiple images into a single merged image is a common requirement for comparison photography, tutorial creation, product showcases, real estate listings, portfolio layouts, before-and-after demonstrations, and social media collages. Creating side-by-side or stacked image comparisons used to require Photoshop or a design application, but the HTML canvas API makes it possible entirely in the browser. The Merge Images tool on OneDocPDF places up to 10 images side by side or stacked vertically with configurable gap size and background colour, without uploading anything to a server.

Horizontal (side-by-side) merge is the most common format for comparison photography. Before-and-after pairs, left-right product variations, A/B design comparisons, and product lifestyle photos flanking the product shot are all natural horizontal merge use cases. The images are aligned by height — shorter images are centred vertically against the tallest image. For the cleanest result, standardise all source images to the same height using the Resize tool before merging.

Vertical (stacked) merge is used for timeline sequences, step-by-step tutorial screenshots, product detail views (front, side, back), and recipe instruction photos. Stacking images in sequence creates a visual narrative that reads naturally top-to-bottom in the same way that text paragraphs flow. Social media carousels sometimes need to be assembled into a single long vertical image for preview purposes. The vertical merge layout handles this by stacking images edge-to-edge with an optional gap.

The gap and background colour settings enable creative compositions beyond simple side-by-side arrangements. A white background with a 30-40px gap between images creates a gallery-print or photo book layout. A black background with zero gap creates the stark cinematic diptych look used in documentary and fine art photography. A light grey background with 20px gaps creates the presentation-slide layout commonly used for product comparison tables and feature showcase rows.

For a complete merging workflow: use Resize Image to standardise dimensions before merging, Compress Image to reduce the merged file size, Add Text to Image to label before/after sections, Watermark to add copyright, and JPG to PDF to compile merged images into a document. All tools are free on OneDocPDF.