BEFORE
Click or drop image here
PNG · JPG · WebP · GIF
VS
AFTER
Click or drop image here
PNG · JPG · WebP · GIF
Upload two images above to start comparing
Supports drag & drop — all processing is done locally in your browser// drag to reveal before & after differences
Drag a slider to reveal differences between before and after images. Upload two images and compare them side-by-side instantly in your browser. Free and private.
BEFORE
Click or drop image here
PNG · JPG · WebP · GIF
AFTER
Click or drop image here
PNG · JPG · WebP · GIF
Upload two images above to start comparing
Supports drag & drop — all processing is done locally in your browserClick the left drop zone or drag an image to set your "before" state.
Click the right drop zone or drag an image to set your "after" state.
Click Compare, then drag the divider handle to reveal differences between the two images.
The Image Comparison Slider lets you overlay two images and drag a divider to reveal the difference. It runs entirely in your browser — no image is ever sent to a server, so your files stay completely private.
No. All image processing happens locally in your browser using the File API and Canvas. Your images never leave your device, making this tool completely private and secure.
Any format your browser can display: PNG, JPG/JPEG, WebP, GIF (first frame), BMP, SVG, and AVIF on supported browsers. Large files may take a moment to load.
Yes. Click the handle to focus it, then use the Left/Right arrow keys (horizontal mode) or Up/Down keys (vertical mode) to move the divider in 1% increments. Hold Shift for 10% jumps.
No. The tool will stretch or fit images into the comparison area using your chosen fit mode: Contain (show full image), Cover (fill area, crop edges), or Fill (stretch to fit exactly).
Yes. Click the Download button to save a PNG snapshot of the current comparison at whatever slider position you have set. The saved image includes both layers as displayed.
There is no hard server-side limit since files never leave your browser. Very large images (over 20 MB) may be slow to render depending on your device's memory and browser.
An image comparison slider is an interactive tool that lets you overlay two images and drag a dividing line to reveal one image beneath the other. It is the standard way to showcase before-and-after transformations — from photo retouching and architectural changes to website redesigns and machine learning model outputs. Rather than switching between two separate images, the slider gives viewers a fluid, side-by-side understanding of how something has changed.
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This tool uses the browser's native File API and HTML Canvas to load your two images entirely on your device. When you drag the slider handle, JavaScript adjusts a CSS clip-path on the "after" image layer, progressively uncovering or hiding it relative to the "before" layer underneath. No pixels are sent to any server at any point. The download feature draws the current view onto a hidden canvas element and exports it as a PNG using canvas.toDataURL().
The tool supports both horizontal (left-to-right) and vertical (top-to-bottom) slider directions. Horizontal is the classic mode used for most before/after photography comparisons. Vertical works well for tall images or when you want to compare sky-to-ground differences — for example, comparing a daytime scene to a nighttime rendering.
Because your two images may have different dimensions, the tool offers three fit modes borrowed from the CSS object-fit property:
Photographers use comparison sliders to show clients the effect of their editing work — skin retouching, sky replacement, color grading, or noise reduction. Architects and interior designers use them to present rendered concepts alongside reference photos. Web developers use them to showcase redesigns: the old site vs the new. AI and machine learning engineers use them to compare model outputs — upscaled images, style transfers, or segmentation masks. The tool is flexible enough for any two-state comparison.
The slider handle is a fully focusable element with proper ARIA attributes (role="slider", aria-valuenow, aria-valuemin, aria-valuemax). After clicking to focus the handle, use the Left and Right arrow keys in horizontal mode, or Up and Down in vertical mode, to move the slider. Hold Shift to jump in 10% increments. This makes the tool usable without a mouse or touch screen.
Many online image comparison tools require you to upload your files to their servers, raising concerns about privacy, confidentiality, and data retention. This tool is different. It operates entirely within your browser tab. Your images are read from disk into browser memory using the FileReader API and are never transmitted over the network. You can use it offline after the page has loaded, and closing the tab discards everything.
For the clearest comparison, use images that are the same resolution and aspect ratio, captured from the same viewpoint. If your images were shot at slightly different angles, even a perfect slider won't make the differences obvious — the eye needs stable reference points to detect change. Use the Cover or Fill mode when both images have matching dimensions. Use Contain when you want to ensure nothing is cropped out. To share a specific moment in the comparison, drag to the position you want and click Download — the exported PNG captures exactly what is visible.