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Web Developers · 25-35% Smaller · Canvas API

Image → WebP

Drop JPG or PNG images below. Conversion happens entirely on your device — no upload, no server, no tracking. Get 25-35% smaller files for faster websites, with a quality slider for full control.

By Keishin · Published

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$ tips

  • Drag multiple JPGs and PNGs at once — they convert one after another so your browser doesn't run out of memory.
  • WebP supports transparency (alpha channel) just like PNG — but at a fraction of the file size.
  • Default quality 85 is the recommended sweet spot for web images. Drop to 75 for image-heavy sites, bump to 95 for crisp graphics.
  • To verify nothing is being uploaded, open DevTools → Network tab before dropping a file. The tab stays empty.
  • The page is fully offline-capable. Save it as a bookmark, disconnect from wifi, and it still converts.

How offline Image to WebP conversion works

This page uses your browser's built-in Canvas API with the WebP encoder — no external libraries, no server upload. When you drop a JPG or PNG, the browser decodes it natively, draws it to an invisible canvas, and exports it as WebP at the quality you choose. At no point does the file leave your device.

Why convert images to WebP?

WebP is Google's modern image format, designed specifically for the web. Compared to JPG and PNG:

  • 25-35% smaller than equivalent-quality JPG/PNG at the same visual quality. This directly translates to faster page loads, less bandwidth, and better Core Web Vitals scores.
  • Supports transparency like PNG, but with much smaller file sizes — even with full alpha channel.
  • Supports animation like GIF, but at 25-35% smaller file sizes and with much better color depth.
  • Recommended by Google for web images. Chrome, Firefox, Safari 14+, and Edge all support WebP natively. Internet Explorer does not — but IE is end-of-life since 2022.

For websites, switching from JPG/PNG to WebP is one of the highest-impact optimizations you can make. Lighthouse audits, PageSpeed Insights, and GTmetrix all recommend WebP.

How to verify it's really offline

You don't have to trust us. Verify it yourself:

  1. Open your browser's DevTools (right-click → Inspect, or F12).
  2. Switch to the Network tab and clear it.
  3. Drop a JPG or PNG onto the converter above.
  4. Watch the Network tab — it stays empty during conversion. No XHR, no fetch, no WebSocket. Nothing.

Alternatively: load this page, then turn off your wifi or unplug your ethernet. The converter still works because everything it needs is already in your browser.

WebP vs JPG vs PNG — which to use?

JPG (Joint Photographic Experts Group) is the universal standard from 1992, supported by literally every device, app, and browser. Use JPG when you need maximum compatibility, are sharing on platforms that don't accept WebP, or working with older software.

PNG (Portable Network Graphics) is the lossless standard from 1996. Use PNG when you need lossless quality (logos, line art, screenshots with text), transparency/alpha channel, or for archival preservation. PNG files are large but pixel-perfect.

WebP is the modern choice for the web. Use WebP for: website images, app assets (where you control the rendering), high-resolution product photos, anywhere you need a good balance of quality, file size, and features (transparency, animation).

The recommended strategy: serve WebP first, fall back to JPG/PNG for browsers that don't support it. Modern HTML makes this trivial with <picture> elements.

Why offline conversion matters for WebP

Most "free JPG to WebP" websites work by uploading your images to their server, converting them there, and sending the WebP back. That's fine for blog post images, but is a problem if your JPGs/PNGs contain:

  • Product photos for an unreleased launch
  • Design mockups under NDA
  • Internal company screenshots
  • Anything you wouldn't share via email with a stranger

With offline conversion, the file is processed entirely inside the privacy sandbox of your browser tab. There is no upload endpoint on our side — the server serves the static HTML/CSS, and your browser does the rest.

WebP browser support and fallbacks

WebP is supported in:

  • Chrome / Edge: full support since 2014
  • Firefox: full support since 2019
  • Safari: full support since 2020 (Safari 14+)
  • Mobile browsers: iOS Safari 14+, Android Chrome — all supported

For maximum compatibility (e.g., supporting old corporate IE installs), use HTML's <picture> element with WebP as the primary source and JPG/PNG as fallback:

<picture>
  <source srcset="image.webp" type="image/webp">
  <img src="image.png" alt="...">
</picture>

Frequently asked questions

Is the image to WebP conversion really offline?

Yes. The converter uses your browser's built-in Canvas API to encode WebP. Once the page loads, all conversion happens locally on your CPU. You can disconnect from the internet and the converter still works — proof that no upload is happening.

Why convert images to WebP?

WebP produces files 25-35% smaller than JPG and PNG at equivalent visual quality. For websites, this means faster page loads, less bandwidth, and better Core Web Vitals scores. WebP is supported by all modern browsers and is the recommended format by Google for web images.

Does WebP support transparency like PNG?

Yes. WebP supports an alpha channel for transparency, just like PNG. Unlike PNG, WebP files are significantly smaller even with transparency. If you need transparent images and small file sizes, WebP is the modern choice over PNG.

Does WebP support animation like GIF?

Yes. WebP supports animation with much better compression than GIF — typically 25-35% smaller. However, WebP animation support is not universal. For maximum compatibility, use GIF for animations. For your own website where you control rendering, WebP is smaller and sharper.

What quality should I use for WebP?

Our converter defaults to 85% quality, which is the recommended balance for web images. Higher values (90-95) preserve more detail at the cost of larger files. Lower values (60-75) produce much smaller files but introduce visible artifacts. For most web use, 80-85 is optimal.

What's the best WebP quality for Core Web Vitals?

Google's Web Vitals initiative recommends WebP with quality 75-85 for most images. Our default of 85% is on the higher end, favoring quality. Drop to 75 if you have a very image-heavy site and need maximum compression.

Is there a file size limit?

No enforced limit, but your browser has practical memory constraints — typically 1-2 GB on a desktop. For typical web-sized JPG/PNG images (under 5 MB each), you can convert hundreds in one session without issues.

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