The audit finding behind slow pages
Images are usually the heaviest part of a web page, and PNG screenshots and photos are among the worst offenders. Site-speed tools like Lighthouse flag large PNGs because WebP typically encodes the same visual quality 25–35% smaller, which translates directly into faster page loads, lower bandwidth use, and better Core Web Vitals scores. Compatibility stopped being an excuse years ago: Chrome, Firefox, Edge, and Safari all display WebP natively, so you can serve it without a PNG fallback for modern audiences. The switch needs no build tooling either — converting the files and updating the references is the whole job.
Step by step
- Open the PNG to WebP converter on SafeFileConvert. It’s free, needs no account, and runs in any current browser.
- Drop your PNGs onto the dropzone, or click it to pick them. You can queue an entire image folder at once rather than converting one file at a time.
- Watch each file report its new size as it finishes. The before-and-after comparison shows exactly how much every image saved, so you’re not taking the 25–35% figure on faith — you can see it per file.
- Download the WebP files individually, or take the whole set bundled into a single ZIP, ready to drop into your site’s assets directory.
What converts well — and what doesn’t
Photographic content and screenshots see the biggest savings; that’s the territory where WebP’s encoder shines. Small flat-color graphics are the honest exception — PNG already compresses those efficiently, so the gains there can be modest. If a particular graphic barely shrinks, keeping it as PNG is a perfectly fine call, and the per-file size readout gives you the numbers to decide with. Transparency is not a concern either way: WebP carries a full alpha channel just like PNG, so logos, icons, and UI cutouts with see-through backgrounds survive the conversion intact, with no white box baked in behind anything.
Your screenshots stay on your machine
The tool doesn’t ship a compression library and doesn’t send files to a server. Each PNG is decoded, drawn onto a canvas, and re-encoded by the WebP encoder built into your own browser — native code, which is why even large screenshots convert quickly. That local pipeline matters more than it might seem, because screenshots routinely show more than intended: private dashboards, inboxes, names, account numbers. Since the image data never travels over the network, no server receives, stores, or logs your files, and closing the tab leaves nothing behind except the WebP files in your downloads folder.