Image Diff -
Compare Two Images & Pictures Online
Compare two images online and spot even the smallest differences between photos, screenshots, and design mockups. Six view modes — side by side, fade, slider, flicker, pixel diff, and details — cover everything from a quick before-and-after to pixel-level visual testing, with no upload and no sign-up.
Your pictures stay completely private: the comparison runs in your browser with nothing sent to a server. That makes it safe for unreleased designs, private photos, medical imagery, and anything you'd rather keep off someone else's servers. No watermarks, no analytics, and nothing kept once you close the tab.
Six Ways To Compare Images And Photos
Pick the view that fits what you're trying to see, and switch between them freely without re-uploading — the same two images flow through every mode.
Side by Side. Both pictures in two panels next to each other, the quickest way to scan for layout, composition, or framing changes.
Fade. Stacks both images and blends between them with an opacity slider, so one picture dissolves into the other — ideal for subtle changes in the same scene.
Slider. Drag a vertical divider to reveal one picture beneath the other — the classic before-and-after swipe for photographers and designers.
Flicker. Auto-toggles between the two images in the same spot so any change appears to jump out; tap space to pause and step through manually. The astronomer's trick for spotting what moved.
Pixel Diff. Highlights every differing pixel over a dimmed original. Heatmap colours each change by how large it is, Difference shows the signed colour delta on grey, and Overlay paints changes in red on top of the original. Changed areas are boxed so you can step through them one by one.
Details. A side-by-side table of every image's metadata, with the differences between the two called out — resolution, format, colour space, DPI, and more.
Pixel-Level Difference Detection
When you need to know exactly which pixels changed, the Diff mode does the work the eye can't. It compares the two images pixel by pixel using a perceptual colour-difference measure (CIE ΔE) rather than a raw RGB subtraction, so it ignores imperceptible noise and flags the changes a person would actually notice. Pixels that only differ because of anti-aliased edges — a font hinted differently, a line shifted by a fraction of a pixel — are detected and set aside, so a re-rendered screenshot doesn't light up on every letter.
A sensitivity slider sets the threshold, Auto-align finds the shift between two screenshots taken at slightly different scroll positions, and Scale to match lets you compare a 1x capture against a 2x one. Changed areas are grouped into regions you can step through with N and P, hover any pixel to read both colours and their ΔE, and the result shows a match percentage, a structural similarity (SSIM) score, and a count of changed pixels. The diff exports as a PNG or copies straight to the clipboard.
Compare Image Details And Quality
Two images can look identical and still differ in ways the pixels don't show. The Details view lays both files' metadata side by side and highlights what changed between them: dimensions and aspect ratio, file size with the exact byte and percent delta, format, colour space, bit depth, alpha channel, chroma subsampling, compression, interlacing, DPI, and EXIF orientation.
That makes it a quick way to compare image quality and file size — checking whether a JPEG-to-WebP conversion held up, why one export is heavier than another, or whether a re-save quietly stripped transparency or changed resolution. It answers the non-visual half of an image comparison that a pixel diff alone can't.
Supported Image Formats
PNG, JPEG, WebP, GIF, AVIF, BMP and SVG all work out of the box, and you can drop in a PDF to compare its first page. HEIC photos open in Safari, where the browser can decode them. Mix formats freely — a JPEG on the left and a WebP on the right compare just fine.
- PNG — Lossless with alpha transparency
- JPEG — Photos and high-colour images
- WebP — Modern web format, smaller than JPEG
- GIF — Simple graphics and short animations
- SVG — Vector graphics, rasterized for pixel diff
- HEIC — Apple photos — Safari only, or convert to JPEG first
How To Compare Two Pictures Online
Four steps — no sign-up, no installation, nothing uploaded.
- 01Add The First Image. Drag a picture onto the left panel, paste from the clipboard, or click to browse. It loads straight into the browser — nothing is sent anywhere.
- 02Add The Second Image. Drop the second picture on the right. Images of different sizes are placed on a shared canvas so any size difference is visible, and Auto-align can line up shifted screenshots.
- 03Choose A Mode. Pick side by side, fade, slider, flicker, pixel diff, or details, and switch between them freely without re-uploading.
- 04Zoom And Inspect. Scroll or pinch to zoom toward the cursor, press 0 to fit and 1 for actual size, and jump between changed regions with N and P. Start with pixel diff to find changes, then flip to slider for a clean before-and-after.
Why Use This Image Compare Tool
Free, private, and watermark-free — built for quick photo comparisons and detailed pixel-level work alike. Eight things make it stand out:
- 01Six View Modes. Side by side, fade, slider, flicker, pixel diff, and details — every way you'd want to compare two images, switchable without re-uploading.
- 02Perceptual Pixel Diff. Differences are detected with a perceptual colour measure, not a raw subtraction, and anti-aliasing noise is filtered out, so it flags changes a person would notice and ignores rendering jitter.
- 03Auto-Align And Regions. Finds the offset between shifted screenshots, groups changes into regions you can step through, and reports match %, SSIM and a per-pixel inspector.
- 04Full Image Details. Resolution, DPI, colour depth, format, colour space, subsampling, interlace, alpha, and EXIF orientation — with the delta between the two images called out.
- 05100% Private. Nothing is uploaded to a server. Safe for unreleased mockups, product photos under embargo, and medical scans — the images never leave the tab.
- 06No Watermarks. Nothing is stamped on your exports. The diff image comes out exactly as rendered, ready to drop into a bug report or review.
- 07Works On Mobile. Pinch to zoom and swipe to pan — every mode works on phones and tablets, not just desktop.
- 08Wide Format Support. PNG, JPEG, WebP, GIF, AVIF, BMP, SVG and PDF pages (HEIC in Safari), mixed freely between the two sides.
Frequently Asked Questions
How do I find differences between two images?
Upload both pictures and open Pixel Diff. Every changed pixel is coloured and the changes are boxed into regions you can step through with N and P. Slider, fade, and flicker are better when you want to see both versions in context rather than just the changes.
Can I compare two photos side by side?
Yes. Side by Side mode places both photos in adjacent panels — the fastest way to do a quick before-and-after — and zoom and pan can be linked so both move together.
Can I compare two images for similarity?
Yes. Pixel Diff reports a match percentage and an SSIM (structural similarity) score from 0 to 1; SSIM stays high for a re-encoded copy that only differs in compression noise, where the raw pixel count would not. It compares the pictures as they are — it is not a facial-recognition or reverse-image match.
What is Flicker mode?
Flicker auto-toggles between the two images in the same spot, so anything that changed appears to jump while everything else stays still — the same trick astronomers use to spot moving objects. Press space to pause and step through the two frames manually.
How does the sensitivity slider work?
Pixel Diff compares images using a perceptual colour-difference threshold. The slider moves that threshold: toward strict to surface only obvious changes, or toward sensitive to catch faint artefacts, watermarks, and sub-pixel shifts that the eye would miss.
Can I compare image quality, size, or format?
Yes. The Details view puts both files' metadata side by side and highlights the differences — dimensions, file size with the exact delta, format, colour space, bit depth, compression, and DPI — so you can compare image quality and weight, not just pixels.
Can I compare pictures of different sizes?
Yes. By default the images share a canvas aligned at the top-left and any area present in only one of them is marked. Turn on Scale to match to compare a 1x screenshot against a 2x one, or use Auto-align when one capture is scrolled or cropped relative to the other.
What formats are supported?
PNG, JPEG, WebP, GIF, AVIF, BMP and SVG, plus the first page of a PDF. HEIC opens in Safari, which is the only browser that can decode it; elsewhere convert to JPEG first. SVG is rasterized at load time so it can be compared pixel for pixel.
Are my images private?
Yes. Everything runs in your browser — your images are never uploaded, stored, or sent to a server. That makes it safe for unreleased designs, embargoed product shots, private photos, and medical imagery.
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