Merge WebP Images
Merge two WebP images online with a per-pixel mask. Transparency is preserved, and you can download the result as WebP, PNG, or JPG. Nothing is uploaded.
Files never leave your browser.
Compose two WebP images by painting a per-pixel mask. The result downloads as WebP by default, but you can pick PNG or JPG instead.
About WebP Merge
Builds one image from two WebP sources. You paint a mask that says which side each region comes from, and the detected differences seed it. The result downloads as WebP, PNG or JPG.
How to use
- Pick a left and a right WebP file of the same size.
- Paint the mask, or resolve each difference group with the buttons next to it.
- Choose the output under Download format: WebP for a small file, PNG for a lossless one, JPG when the target cannot read WebP.
What this tool doesn't handle
- An animated WebP is read at its first frame, so only that frame is merged.
- A WebP download is encoded again and is not pixel-identical to the sources. Choose PNG when the result must stay exact.
Frequently asked questions
Do my files ever leave my browser?
No. Every comparison runs locally in your browser. Nothing you paste, drop, or load is uploaded to a server; the tool keeps working even if you go offline after the page loads.
Is this tool free to use?
Yes. All DiffResolver tools are free, with no account, sign-up, or installation. Because processing happens on your device, there are no server-imposed usage limits.
Which formats can the merged image be saved as?
WebP, PNG or JPG. The format selector sits next to the Download button and starts on WebP here. PNG is the lossless choice, and JPG drops transparency.
Is transparency kept in the merged WebP?
Yes. WebP stores an alpha channel, so a transparent region of either source stays transparent. A JPG download flattens it over white instead.
What if the reader of my file cannot open WebP?
Every current browser reads WebP, but older applications may not. Set Download format to PNG or JPG and the merged image is written in that format.
Is there a file size limit?
No server limit applies, because nothing is uploaded. The memory of your device sets the practical limit. Above 10 MB for text, 40 MB for images, 100 MB for documents, or 500 MB for archives, the tool warns you that the work can be slow, but it never blocks the file.
Does this tool work offline?
Yes. The browser keeps a copy of the tool after the first visit, so a page you opened before still works without a network. You can also install DiffResolver as an app from the browser menu. Installation stays optional; the site works the same in a normal tab.
Where is my data stored?
Your files are stored nowhere. They stay in the memory of the page and are gone when you close the tab. Only what you save yourself stays in this browser: a snapshot, your tool options, and your theme. To remove it, open Settings and select Clear all local data.