What this tool does
Drop up to ten files of any kind and everything that can become a picture comes back as WebP. A mixed folder is fine: iPhone HEIC photos, PNG screenshots, scanner TIFFs, AVIF images saved from a website, SVG logos and PDF pages can all go in at once. Files that cannot become an image are listed with the reason rather than quietly disappearing.
Every result has its own download button, and there is a single ZIP when more than one converted. Decoding and re-encoding happen in your browser, so nothing is uploaded — which is the difference that matters when the batch is a client's product photography.
Why WebP
WebP reaches the same visual quality as JPG in roughly 25 to 35 per cent fewer bytes, and unlike JPG it supports transparency. For a website that is a large, free saving: images are usually most of a page's weight, and halving them is the single biggest thing you can do for how fast the page feels.
| Same photograph | Typical size | Transparency |
|---|---|---|
| PNG | 24 MB | Yes |
| JPG at quality 0.85 | 2.5 MB | No |
| WebP at quality 0.85 | 1.7 MB | Yes |
| AVIF at quality 0.85 | 1.1 MB | Yes |
Every current browser displays WebP, so for anything shown on the web it is the sensible default. The place it still bites is outside the browser: some upload forms, older desktop software, print workflows and email clients reject it. If the file is going to a person rather than a web page, JPG or PNG is the safer target.
What goes in and what comes out
| You drop | You get | Note |
|---|---|---|
| JPG, PNG, BMP, GIF | One WebP per file | GIF gives the first frame, not the animation |
| HEIC / HEIF from an iPhone | One WebP per photo | No Windows codec needed |
| TIFF from a scanner | One WebP per file | First image in the file |
| AVIF | One WebP per file | Usually slightly larger than the AVIF it came from |
| SVG | One WebP at the artwork's own size | Keep the SVG as the master for anything that scales |
| One WebP per page, up to 20 pages | Rendered at 2× | |
| MP4, MOV, WebM and other video | One WebP still frame | Taken a few seconds in, not the opening frame |
| Word, Excel, audio, archives | Skipped, with a reason | Nothing inside to render |
Picking a quality setting
- 0.90 and above — near-indistinguishable from the source, but the file grows quickly for differences nobody sees. Worth it only for large hero images.
- 0.80 to 0.85 — the usual choice for photographs on a website. Visually clean at normal viewing size.
- 0.70 to 0.75 — noticeably smaller, fine for thumbnails, listings and anything displayed small.
- Below 0.60 — smoothing becomes visible in skies, skin and flat areas. Use only when a hard size limit forces it.
One rule beats any quality setting: reduce the pixel dimensions first. An image displayed 800 pixels wide gains nothing from being 4000 pixels wide, and halving width and height removes three quarters of the data at no visible cost — far more than any compression setting can save.
What a video file gives you
Drop an MP4, MOV, WebM or anything else your browser can play and you get one still frame back, taken a few seconds in rather than at zero — the opening frame of a recording is very often black or a fade, which makes a useless thumbnail. It is the quick way to get a poster image out of a clip without opening a video editor.
It is a still, not a converted video. Turning an MP4 into a WebM, trimming it or changing its resolution is transcoding, and doing that inside a browser means shipping a WebAssembly build of FFmpeg — roughly 25 MB before any video is touched, with the memory use to match. That is a poor trade on a phone, so this tool does the part that is genuinely quick and says plainly that it does not do the rest. A file in a codec no browser ships, which is true of some MKV and AVI files, is skipped with a reason rather than producing a blank frame.
The ten-file limit
The work runs on your device in one browser tab. Ten at a time keeps a round fast and stops a phone running out of memory partway through, which would cost the whole batch rather than one file. Larger jobs are simply several rounds — nothing is uploaded, so there is no queue between them. If you drop more than ten, the first ten are taken and the tool says how many were left over.