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Image Comparison Slider

Compare two images side by side with a draggable slider. Perfect for before/after comparisons. No upload — files stay on your device.

Drop Before image

Drop After image

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Image comparison sliders — also called before/after sliders or reveal sliders — display two images overlaid on the same canvas, with a draggable divider that controls how much of each image is visible. Dragging left reveals more of the 'before' image; dragging right reveals more of the 'after'. This technique is significantly more informative than presenting two images side by side because it eliminates parallax: both views are perfectly aligned at pixel level.

The slider effect is implemented using a CSS clip-path on the top image layer: as the divider position changes, the clip rectangle is updated to reveal more or less of the after image while the before image remains fully visible underneath. This approach requires no canvas operations — both images render at their natural resolution, and the comparison is purely a presentation layer effect with no quality loss.

This tool implements the comparison slider entirely in the browser. After uploading both images, the divider can be dragged to compare them. The labels ('Before' and 'After') are editable to match any comparison context. Images never leave the browser — all processing uses the browser's native image rendering. Common applications include photo retouching review, web design before/after, medical imaging comparison, and real estate renovation documentation.

Common Use Cases

Photo retouching and editing review

Photographers and retouchers use before/after sliders to present the impact of their work to clients. Showing the original and edited image in a comparison slider demonstrates specific improvements — skin retouching, color grading, background removal — without requiring the viewer to flip between two separate files. The slider reveals the transformation interactively, making the editing value immediately apparent.

Web design and UI redesign presentations

UX designers presenting a redesigned interface to stakeholders use comparison sliders to show the old design versus the new design on the same reference point. When both mockups are the same dimensions and represent the same page, the slider eliminates any doubt about which elements changed and demonstrates the visual evolution directly rather than asking reviewers to compare two separate screenshots.

Document and map change detection

Satellite imagery analysts, urban planners, and document reviewers compare two versions of a map or scan using sliders to detect changes: new construction, deforestation, document alterations. The slider technique precisely aligns before and after images and lets the analyst scrub across the boundary to trace exactly where and how the content differs.

How to Use

  1. Upload Image A (the “before” image) to the left drop zone.
  2. Upload Image B (the “after” image) to the right drop zone.
  3. Optionally, edit the labels (Before / After) to match your content.
  4. Once both images load, drag the slider to reveal more of Image A or Image B.
  5. Everything runs in your browser — no images are uploaded to any server.

Common Use Cases