Free Before & After Image Slider — compare two photos online
A liquid wipe, a magnifier lens, and a change heatmap — GPU-rendered, buttery at 60fps, and 100% private. Embed it on your own site free.
How it works
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Drop in two images
Before and after — drag & drop, click, or paste from your clipboard. Nothing is uploaded anywhere.
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Compare four ways
Liquid wipe, magnifier lens, crossfade — or "What changed?", a heatmap that lights up every pixel that differs.
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Export or embed
Download the view as an image, or copy a two-line snippet and put the interactive slider on your own website.
One slider, every industry
Before-and-after photos are the most convincing content there is — when people can interact with them. A static side-by-side makes viewers do the work; a draggable slider makes the change land instantly. This tool gives you that slider in your browser, and — unlike other comparison tools — lets you embed the same interactive widget on your own website for free.
- Real estate & property staging — show empty versus staged rooms, or listing photos before and after a refresh.
- Renovation & trades — kitchens, bathrooms, gardens, driveways. A slider on your quotes page sells the next job.
- Aesthetics clinics & dental — treatment results with total privacy: patient photos never leave the device you're working on.
- Web agencies — redesign reveals for case studies, and screenshot diffs for QA. The "What changed?" heatmap catches a moved button in a sea of pixels.
- SEO & content teams — compare SERP or page screenshots across time and spot every layout shift.
Why it feels different
The viewer runs on your graphics card with a custom WebGL engine. The wipe divider ripples like liquid as you drag, the lens refracts at its rim like real glass, and the change heatmap is computed per-pixel in real time — no processing wait, no quality loss, even on 4K images. If a browser can't do WebGL, the tool quietly falls back to a simple slider, so it never breaks.
The embed
Everything above works on your own website too. Host your two images, paste two lines of HTML, and the same GPU-rendered slider appears on your page — 16KB, no dependencies, no account. It's how this tool spreads, and it's free forever.
FAQ
Common questions
Do my photos get uploaded?
No. Both images are opened directly by your browser and drawn onto your own graphics card — nothing is sent to Monity or anyone else. Close the tab and they're gone. That makes this safe for client work, medical photos, and anything under NDA.
Can I embed this on my website?
Yes — free. Load a comparison, open "Embed this on your website", and copy the two-line snippet. Host the two images on your own site, paste the code, done. The widget is a single 16KB script with no dependencies and shows a small "Powered by Monity" badge.
Is it really free?
Completely — the tool and the embed. No signup, no watermark on your exported images, no limits. Monity makes money from its website monitoring product, not from this.
Can I compare two versions of a web page?
Manually: screenshot both versions and drop them in — the "What changed?" mode will light up every difference. Automatically: Monity screenshots any page on a schedule and alerts you with this exact kind of visual diff the moment something changes. The free plan includes 3 monitors.
Why doesn't the fancy effect show on my embed?
Browsers only let the graphics card read images that come from the same website as the page, or from a server that explicitly allows it (CORS). If your two images live on a different domain without that permission, the widget quietly switches to a simple slider instead of breaking. The fix is easy: host both images on the same site as the page that embeds them.
Comparing changes by hand?
Let Monity spot them.
Monity screenshots any web page on a schedule and alerts you the moment something changes — with this exact visual diff.
- Free 7-day trial
- No credit card
- 3 monitors free, forever