How to compare two images or videos
No account, no install, no upload — three steps.
1. Add your first file
Drop an image or video into slot A, or click the slot to browse. You can also drag both files in at once and the second one fills slot B automatically. Nothing is sent anywhere when you add a file — the browser simply reads it from disk.
2. Add the file to compare against
Drop the second file into slot B. This is usually the "after": a compressed export, an AI-upscaled result, a different codec, or a re-touched version. Mixing an image with a video is allowed if you want to check an exported frame against its source.
3. Open the fullscreen viewer
Click Start Comparing. Drag the slider across the frame, or switch to split view to see both halves at once. Scroll to zoom, drag to pan, and double-click to toggle 1:1 — both files stay perfectly in step.
Which comparison mode should you use?
Slider view — best for spotting fine differences
Both files are stacked in exactly the same position, and the second one is revealed as you drag the handle. Because every pixel lands where its counterpart was, your eye catches changes it would otherwise miss: compression blocking in a gradient, smeared texture detail, halos along high-contrast edges, or a subtle shift in colour grading. This is the mode to use when you are deciding whether a quality setting is good enough.
Split view — best for judging overall impression
The two files sit side by side in a shared viewport, so nothing is ever hidden. Use it when the question is about the whole frame rather than a detail — framing, brightness, how a scene reads at a glance — or when you are showing someone else the difference and do not want to be dragging a handle around while you talk.
Both modes share one zoom level and one pan offset, so you are always looking at the same region of both files; video additionally shares a single timeline, so the two players stay on the same frame instead of drifting apart. In the viewer: scroll to zoom · drag to pan · double-click to toggle 1:1 · Space to play or pause video · Esc to exit.
What people use it for
JPEG vs WebP vs AVIF quality
Put the original next to a JPEG, WebP or AVIF export and find the exact quality setting where artefacts start to become visible.
AI upscaling and restoration
Check whether an upscaler recovered real detail or simply invented plausible-looking texture that was never in the source.
Video codecs: H.264 vs H.265 vs AV1
Compare H.264 against HEVC (H.265) or AV1 at the same bitrate, or one codec at two bitrates, with both clips locked to a shared timeline.
Photo edits
Review a retouch, a colour grade, or a denoise pass against the untouched original before you commit to it.
Screenshot regressions
Diff a UI screenshot from before and after a change to catch unintended layout, spacing or rendering shifts.
Camera and lens tests
Compare two exposures of the same scene at 1:1 to evaluate sharpness, noise behaviour or how a lens renders detail.
Design variants and A/B tests
Place two design drafts or ad creatives side by side and compare layout, hierarchy and colour at the same zoom level before deciding which one ships.
Watermark and filter checks
Verify that a watermark, LUT or filter landed exactly where it should by overlaying the treated version on the untreated one in slider view.
Supported formats
Decoding is handled by your browser, so anything it can display, this tool can compare.
Images
JPEG · PNG · WebP · AVIF · GIF · BMP · SVG
Video
MP4 (H.264) · WebM (VP8, VP9, AV1) · MOV
Not supported
HEIC/HEIF (Safari only) · ProRes · RAW — convert these first
If a file will not load, it is a codec limitation of the browser rather than a size or duration limit. There is no cap on file size or resolution, because the work happens on your own hardware.
Everything runs in your browser
Your files are read directly by the page and rendered on your own device. This site has no upload endpoint and no server-side component that could receive a file, so nothing is transmitted, stored or inspected — not by us, not by anyone. You can disconnect from the network and the tool keeps working.
That matters most for the material people actually want to compare: unreleased product shots, client work under NDA, medical or legal imagery, personal photos. It also means there is no file size ceiling and no queue, since there is no server doing the work.
There are no accounts, no cookies and no analytics. Your language choice travels in the URL, and the only thing kept on your device is which view mode and theme you last used.
Frequently asked questions
- Are my files uploaded to a server?
- No. All processing happens locally in your browser, and this site has no upload endpoint at all. Your files never leave your device — you can verify it by disconnecting from the network and using the tool offline.
- Is there a file size limit?
- There is no limit imposed by the tool. Because comparison runs on your own device, the practical ceiling is your available memory — very large videos may feel sluggish on a phone but are usually fine on a desktop.
- Can I compare a video against an image?
- Yes. Mixing an image and a video is supported: the video plays on the shared timeline while the image stays still. This is useful for checking an exported still frame against its source footage.
- Does it work on a phone or tablet?
- Yes. The layout adapts to small screens and the viewer supports touch gestures — drag to move the slider, pinch to zoom, and drag with two fingers to pan.
- Why will my HEIC or ProRes file not load?
- Decoding is done by your browser, so the tool supports exactly the formats your browser supports. HEIC works only in Safari, and ProRes is not supported in browsers at all. Convert the file to JPEG, PNG, MP4 or WebM first.
- Do I need an account, and is it free?
- No account is needed and the tool is completely free. There is no sign-up, no paid tier, no usage quota and no watermark. Since the computation happens on your hardware, each comparison costs us nothing.
- Can I use it offline?
- Yes, via the Chrome extension. It packages the same tool for offline use, which is handy when you are working with confidential material on a disconnected machine.
- How do I get a pixel-accurate look at a small area?
- Scroll to zoom into the region you care about, then double-click to toggle 1:1 so one image pixel maps to one screen pixel. Zoom and pan stay synchronised across both files, so you are always inspecting the same spot.
- How do I compare two images side by side online?
- Drop both images into the two slots on this page — nothing is uploaded, the files are read straight from disk — then click Start Comparing. Use split view to see them side by side, or slider view to overlay them and drag between the two.
- Can I compare two videos frame by frame?
- Yes. Both videos share a single timeline, so pausing and scrubbing the progress bar moves them to exactly the same frame. Combined with zoom and 1:1 mode, you can inspect a single frame of both encodes pixel by pixel.
- JPEG, WebP or AVIF — which one should I export?
- It depends on the image. Export the same picture in each format at similar file sizes, then compare the results pairwise at 1:1: gradients and flat areas reveal compression blocking first, while fine texture shows where detail is being smeared. That is exactly the comparison this tool is built for.
- What is the difference between slider view and split view?
- Slider view stacks both files in the same position and reveals one as you drag the handle — best for spotting fine pixel-level differences. Split view places them side by side with nothing overlapping — best for judging the overall look of the whole frame. Zoom and pan stay synced in both modes.