Convert multiple images between PNG, JPG, WebP, and AVIF in one batch with ZIP output.
This tool takes a batch of images you drop in - any mix of PNG, JPG, WebP, or AVIF source files - and re-encodes each one into whichever target format and quality you choose, then bundles all the results into a single ZIP you download in one go. Conversion happens by drawing each image onto a canvas and exporting it in the new format, so files never leave your browser. The most common surprise: AVIF encoding isn't supported in every browser, and converting a PNG or WebP with transparency to JPG silently fills the transparent areas solid, since JPG has no alpha channel.
A concrete input and expected output from the current implementation.
Input
3 files dropped in: photo1.png, photo2.png, icon.png (icon.png has a transparent background) - target format WebP, quality 80
Expected output
download.zip containing photo1.webp, photo2.webp, icon.webp, each re-encoded at quality 80. icon.webp keeps its transparent background.
Base filenames are preserved, only the extension changes to .webp - but the pixel data itself is not untouched, since quality 80 is a lossy WebP setting and canvas re-encoding also drops metadata such as EXIF tags and embedded color profiles. WebP supports an alpha channel like PNG, so icon.png's transparency carries over intact, which would not happen if the target were JPG.
Each source file is loaded into the browser and drawn onto an off-screen canvas, then exported through the canvas's blob-encoding step with the target format and quality you set. This is why the tool can convert between any of PNG, JPG, WebP, and AVIF in either direction - it isn't rewriting file headers, it's fully decoding pixels and re-encoding them.
Instead of triggering a separate download per file, the tool processes the whole batch and packages every converted output into one ZIP archive, offered as a single download. Original filenames are kept with the new extension swapped in, so you can match outputs back to inputs after unzipping.
Usually for photos, but not guaranteed. Screenshots, graphics, or images with large flat-color areas or transparency can end up looking worse or not much smaller in JPG. WebP or AVIF at the same visual quality will usually beat both PNG and JPG on file size.
There's no hard-coded limit, but everything runs in your browser tab's memory, so very large batches or very large source images can slow the tab down or cause it to run out of memory. Dozens of typical web-sized images at a time is a safe range; thousands is not.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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