Free WebP & AVIF Converter (Fix Lighthouse Warnings · Bulk JPG/PNG Conversion · No Uploads)
Fix Google Lighthouse warnings instantly. Bulk convert legacy JPG/PNG images to next-gen formats locally in your browser — zero uploads, zero server logs.
WebP & AVIF Conversion — Quick Reference
- ►WebP vs AVIF savings: WebP reduces file size ~30% vs JPG; AVIF reduces ~50% — both fix the Google Lighthouse "serve images in next-gen formats" warning
- ►Browser support: WebP is supported by ~96% of browsers (safe default); AVIF by ~93% — always pair with a JPG fallback using the
<picture>element - ►Lighthouse warning fix: Convert your JPG/PNG assets to WebP or AVIF, re-upload to your server, then re-run PageSpeed Insights — the warning resolves immediately
- ►Shopify & WordPress: Shopify CDN serves WebP automatically; WordPress 5.8+ accepts WebP uploads natively — pre-converting before upload gives you full quality control
- ►Transparency support: WebP fully supports alpha channel transparency — it is a direct drop-in replacement for transparent PNGs at ~30% smaller file size
- ►
<picture>fallback: Use<source srcset="img.avif" type="image/avif">+<source srcset="img.webp" type="image/webp">+<img src="img.jpg">for universal compatibility - ►When to use each: Use WebP for all standard images; use AVIF for hero banners and large images where every KB matters for LCP Core Web Vitals scores
Convert instantly: Free PixelBatch WebP/AVIF Converter — bulk, private, no uploads.
Drop JPG/PNG images here
Bulk convert to next-gen WebP or AVIF format
Conversion Successful!
Download Converted FilesHow to Fix the "Serve images in next-gen formats" Warning
If you are a web developer or a WordPress site owner, you have likely run your site through Google PageSpeed Insights (Lighthouse) and seen a massive red penalty for your images. Legacy formats like JPEG and PNG were created decades ago and lack the advanced compression algorithms required for the modern, mobile-first web.
WebP vs. AVIF: Which Should You Choose?
The two dominant next-gen formats are WebP (created by Google) and AVIF (created by the Alliance for Open Media). Here's how to choose:
The Case for WebP
WebP is the industry standard. It provides up to 30% smaller file sizes compared to JPEG, supports transparency (unlike JPEG), and is supported by ~96% of all global browsers. It also integrates natively with Shopify's CDN and WordPress 5.8+. If you want a safe default, choose WebP.
The Case for AVIF
AVIF is the bleeding edge. It offers significantly better compression than even WebP, meaning your files will be astonishingly small without visible quality loss. Browser support sits around 93%. Use AVIF for hero images and large banners where saving every kilobyte has a direct impact on LCP scores.
How to Implement WebP with a JPG Fallback
Once you've converted your images, you need to serve them correctly in your HTML. Use the picture element to serve WebP/AVIF to modern browsers while automatically falling back to JPG for older ones:
<picture>
<!-- AVIF: best compression for modern browsers -->
<source srcset="image.avif" type="image/avif">
<!-- WebP: fallback for browsers without AVIF -->
<source srcset="image.webp" type="image/webp">
<!-- JPG: universal fallback for legacy browsers -->
<img src="image.jpg" alt="Description" loading="lazy">
</picture>Browsers read the source tags from top to bottom and use the first format they support. This means modern Chrome and Safari users get AVIF, Firefox users get WebP, and the rare IE11 user gets the JPG — all from a single block of HTML.
Why PixelBatch is Safer than Cloud Converters
Most free converters require you to upload your files to their servers. If you are an agency working with unreleased product photos or confidential client assets, uploading them to a random server is a significant security and NDA compliance risk.
PixelBatch is 100% Client-Side. Using WebAssembly, we load the conversion engine directly into your browser. When you drop 50 images into the tool, your computer's CPU does the work — zero uploads, zero server logs, absolute privacy. Need to embed tiny icons directly into CSS without HTTP requests? Try our Base64 Encoder tool for that use case.
The Next-Gen Image Optimization Checklist
Follow these steps to guarantee maximum Core Web Vitals improvements.
Format Selection
Convert standard photos to WebP for maximum compatibility. Reserve AVIF for massive hero banners where saving every kilobyte counts for LCP scores.
80% Quality Sweet Spot
Our tool defaults to 80% quality — the universally accepted point where file sizes drop dramatically but the human eye cannot detect any difference in sharpness.
Implement the <picture> Fallback
Always use the HTML <picture> element with a JPG <img> fallback alongside your WebP/AVIF sources to support the remaining 4-7% of older browsers.
Client-Side Privacy for NDA Assets
Never upload unreleased product photos or client designs to a cloud converter. PixelBatch ensures your assets remain on your local device during conversion, maintaining full NDA compliance.
Average Size Savings vs JPG
Results vary based on image complexity.
Frequently Asked Questions
Is AVIF better than WebP? ▼
Yes, AVIF generally offers up to 30% better compression than WebP, resulting in smaller file sizes at the exact same visual quality. However, WebP currently has slightly broader browser support — around 96% vs AVIF's 93% — making WebP the safer default for most websites.
How do I fix the 'Serve images in next-gen formats' warning? ▼
Google Lighthouse triggers this warning when it detects heavy legacy JPG or PNG files blocking your page load. Drop your images into our converter above, export them as WebP or AVIF, then replace the old files on your web server. Re-run PageSpeed Insights to confirm the warning is resolved.
Does converting to WebP affect image quality? ▼
At 80% quality (our default), WebP conversion produces visually lossless results that the human eye cannot distinguish from the original. File sizes are typically 25–35% smaller than the equivalent JPEG. If you need pixel-perfect lossless output, set quality to 100% before converting.
Can I convert a PNG with transparency to WebP? ▼
Yes. Unlike JPEG, WebP fully supports alpha channel transparency. When you convert a transparent PNG to WebP, the transparency is preserved perfectly. This makes WebP an ideal replacement for transparent PNGs — smaller file sizes without losing the transparent background.
Does Shopify automatically convert images to WebP? ▼
Yes, Shopify automatically serves WebP via its CDN. However, Shopify applies its own compression on top of your uploaded files. For best results, upload pre-optimized WebP files directly — this gives you full control over quality and file size before Shopify's secondary compression is applied. Use our Shopify Grid Resizer first to get the correct 2048px square format, then convert to WebP here.
Should I use WebP or AVIF for WordPress? ▼
For WordPress, WebP is the recommended choice. WordPress 5.8+ natively supports WebP uploads. Most popular plugins (Imagify, ShortPixel, Smush) also output WebP. AVIF support in WordPress is more limited and requires additional server-side configuration.
Does this tool support bulk or batch conversion? ▼
Yes. Because PixelBatch processes images locally using your device's hardware via WebAssembly, you can drag and drop dozens of images at once and convert your entire media library to WebP or AVIF in seconds without hitting artificial cloud paywalls.
Will WebP and AVIF images work on older browsers? ▼
WebP is supported by over 96% of global web browsers, while AVIF is supported by around 93%. For older browsers like IE11, use the HTML <picture> element with a <source> tag for WebP/AVIF and an <img> fallback pointing to the original JPG. See the code example in the content section above.
Is it safe to convert unreleased client images here? ▼
Absolutely. PixelBatch is 100% client-side. We do not have an upload server. Your images, unreleased product shots, and client assets never leave your computer, ensuring total privacy and NDA compliance.