WebP Express plugin review and common issues

Go to WebP Express → Settings → Test Converters. The plugin tests each available conversion method (cwebp binary, imagewebp PHP function, gmagick, imagick, vips) and shows which are working. If none work, contact your hosting provider — ask if they can enable GD with WebP support, install the cwebp binary, or enable the Imagick PHP extension. Most modern managed hosts support at least imagewebp via GD. Cheap shared hosts with minimal server configuration may not support any method without a hosting upgrade.

WebP serving via .htaccess requires Apache with mod_rewrite enabled and AllowOverride set to All. Check: (1) your server uses Apache, not Nginx — .htaccess rules do not apply on Nginx; (2) go to WebP Express → Settings → Serving and verify the .htaccess rules were written correctly; (3) use a browser DevTools Network tab and check the Accept request header — if it includes image/webp, your browser supports it; (4) check the response Content-Type header — if it still shows image/jpeg, the .htaccess rule is not firing. For Nginx, switch to the “picture tags” serving method in WebP Express settings.

WebP compression sometimes produces larger files than JPEG for certain image characteristics — particularly small images, images with large flat color areas, or already-highly-compressed JPEGs. WebP Express has a quality setting (default 80) that can be lowered to produce smaller WebP files. In extreme cases, disable WebP serving for images where WebP is consistently larger — WebP Express has a “do not serve if larger” option that falls back to the original format.

On Nginx, .htaccess rules do not apply. In WebP Express → Settings → Serving, switch the serving method to “Picture tags.” This method uses JavaScript or PHP to replace img tags with picture elements that include a WebP source and a fallback. Alternatively, if you have access to your Nginx configuration, add server-block rules to check for WebP file existence and set the Accept header — WebP Express documentation includes the exact Nginx configuration snippet. Picture tags are the simplest approach without server-level access.

WebP Express is specifically designed for WebP format and does not generate AVIF. For AVIF conversion, use ShortPixel (which includes AVIF support) or Imagify’s AVIF mode. You could theoretically use WebP Express for WebP alongside a separate AVIF plugin, but managing two format conversion plugins adds complexity. For a complete next-gen image format solution without multi-plugin complexity, an all-in-one optimizer with native AVIF support is simpler.

If you use ShortPixel with WebP conversion enabled, or Imagify at a paid tier with WebP, those plugins generate and serve WebP natively — WebP Express is redundant. WebP Express fills the gap for users on free tiers of optimization plugins that do not include WebP serving, or for those using EWWW Image Optimizer’s local mode without the Easy IO CDN. If your optimization plugin already handles WebP, do not install WebP Express in addition.

Initial bulk conversion of an existing media library is CPU-intensive and should be run during low-traffic periods. The conversion runs asynchronously in the background, so it does not block page load for visitors. After initial conversion, only newly uploaded images are converted — the impact is minimal. On-demand conversion (converting the first time an image is requested rather than in bulk) adds slight latency to the first WebP request per image but avoids bulk conversion load.

Yes, that can happen, especially on older sites with many plugins. This usually happens when the plugin, theme, and add-ons are updated out of sequence. In most cases, testing on staging catches the issue before it reaches the live site. From experience, backups and changelog reviews save a lot of cleanup time.

Start by checking whether another plugin already does the same job. In most cases, overlap is what creates avoidable conflicts and performance issues. A common issue is installing a plugin because it looks convenient without checking the stack first. From experience, a short compatibility review avoids most of the pain later.