Batch-Convert Images to WebP and AVIF Free (MooCrunch)

You can convert images to WebP or AVIF in your browser, a whole folder at a time, without installing anything and without uploading a single file. MooCrunch is ClipCraft's batch image converter, and every byte of the work happens in your own tab. I ran four photos through it for this post (about 8 MB of JPEGs and a PNG), and the batch came out 74% smaller as WebP and 91% smaller as AVIF. Those numbers are in the screenshots below, not rounded up for marketing.

Why bother with WebP or AVIF at all

File size, mostly. A JPEG re-saved as WebP usually lands 25 to 35% smaller at the same visible quality, and AVIF goes further still. Smaller images mean faster pages, and page speed feeds directly into how Google ranks you and how many visitors stick around. Every screenshot on this blog is an AVIF for exactly that reason; the four in this post range from 12 KB to 60 KB at 1600px wide.

The catch with most converters is the upload. You hand your photos to some server, wait for the round trip, and hope the site's privacy policy means anything. MooCrunch skips all of that. The decoding and encoding run on your own machine (the WebP encoder is libwebp, the same one the popular server tools use), so a 200-photo batch never touches the network.

How to convert images to WebP in one batch

1. Create a free ClipCraft account(the tool is sign-in gated, but there's nothing to pay).
2. Open Tools → MooCrunch.
3. Drag images or an entire folder onto the drop zone. There's a recursive toggle if you want subfolders scanned too, and duplicate drops get skipped automatically.
4. Click WebP (or AVIF) in the output bar. The batch reprocesses on the spot.
5. Download files one at a time, or hit Download All for a ZIP that keeps your folder structure (a flat option exists if you prefer).

Here's my four-file test after switching the output to WebP. The three JPEGs dropped between 61 and 69%, and the PNG product shot went from 2.2 MB to 17.8 KB, a 99% cut, because flat-color PNGs are exactly what lossy WebP eats for breakfast.

WebP or AVIF, which should you pick?

Same batch, output switched to AVIF: total savings jumped from 74% to 91%. The sunset JPEG that WebP took to 582.7 KB came out at 198.2 KB as AVIF, and a dark night shot fell from 1.3 MB to 43.7 KB. AVIF is simply a better codec, and every current browser displays it.

So why not always AVIF? Two reasons. Encoding is slower; the AVIF encoder runs as WebAssembly and my little four-file batch took noticeably longer than the near-instant WebP pass, so budget some patience for a hundred vacation photos. And a few older apps and CMSes still reject .avif uploads while accepting .webp everywhere. My rule: AVIF for anything I serve on my own site, WebP when the file has to travel through other people's software.

Dial in a single image with the Custom view

Batch settings are guesses, good ones, but guesses. Click Custom on any row and you get a Squoosh-style editor: the original on the left, the compressed preview on the right, and a draggable divider between them so you can hunt for artifacts at any zoom level. A quality slider and a width slider sit below, with the new file size updating live in the corner. I pulled the sunset JPEG down to quality 80 and watched it go from 1.8 MB to 80 KB while the two halves stayed visually identical at 100% zoom.

There's an Apply to All button once you find settings you like, so one careful decision can drive the whole batch. Resizing works the same way: set a width in pixels and it scales down (never up), which is usually where the biggest savings hide. A 4000px camera photo displayed 800px wide is wasted bandwidth no codec can fix.

iPhone photos, and the other formats it reads

MooCrunch decodes PNG, JPEG, WebP, AVIF, GIF, TIFF, SVG, and HEIC. That last one matters more than it sounds: iPhones shoot HEIC by default, half the web can't display it, and the usual fix is some ad-covered upload site. Here you drop the .heic files in and download JPEGs or WebPs a moment later, photos of your kids never leaving your machine. Output formats are WebP, AVIF, PNG, and JPEG; it won't write TIFF or GIF, since browsers have no clean encoder for either.

One honest limitation: metadata doesn't survive conversion. A browser canvas can't carry EXIF data through a re-encode, so camera settings and GPS tags get stripped. For web publishing that's a feature (smaller files, no location leaks), but archive your originals if the EXIF matters to you. The Download Originals button builds a backup ZIP for exactly that. If you want the GPS data handled deliberately instead, that's a separate ClipCraft tool.

A few extras worth knowing about: a prefix/suffix renamer that applies to every download, a per-row rotate button, and a Turbo Mode in the drawer that trades visible quality for extreme compression. Turbo is fine for throwaway thumbnails and too aggressive for anything you care about.

What it costs

There are no tokens involved and no watermark on the output. A batch costs one tool use, whether it's three photos or three hundred, and the free plan includes one tool use a month; paid plans raise that to 5, 20, or unlimited. If image cleanup is a monthly chore rather than a daily one, the free tier genuinely covers it. Sign up, crunch your folder, done.

If the browser-does-everything approach appeals to you, it runs through the rest of the toolkit too: the PDF compressor shrinks documents without uploading them, the photo editor is a full layers-and-masks affair in a tab, and the background remover handles the one job that does need a GPU.