{"id":123048,"date":"2026-06-04T08:16:06","date_gmt":"2026-06-04T08:16:06","guid":{"rendered":"https:\/\/make.wordpress.org\/core\/?p=123048"},"modified":"2026-06-04T12:47:42","modified_gmt":"2026-06-04T12:47:42","slug":"call-for-testing-client-side-media-processing","status":"publish","type":"post","link":"https:\/\/make.wordpress.org\/core\/2026\/06\/04\/call-for-testing-client-side-media-processing\/","title":{"rendered":"Call for Testing: client-side media processing"},"content":{"rendered":"

Client-side media processing is a progressive enhancementenhancement<\/span> Enhancements are simple improvements to WordPress, such as the addition of a hook, a new feature, or an improvement to an existing feature.<\/span><\/span><\/span> to WordPress\u2019s existing server-based media pipeline. When a user uploads an image in the blockBlock<\/span> Block is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage using the WordPress editor. The idea combines concepts of what in the past may have achieved with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience.<\/span><\/span><\/span> editor, their browser decodes, resizes, and encodes all sub-sizes locally using the VIPS image processing library running in WebAssembly (via wasm-vips<\/a>) before sending them to the server. Browsers that can\u2019t handle the work silently fall back to the existing server-side path without user-visible errors.<\/p>\n\n\n\n

The advantage of this approach is that we can provide a uniform, modern image processing experience across all WordPress sites without relying on server-side capabilitiescapability<\/span> A\u00a0capability<\/strong>\u00a0is permission to perform one or more types of task. Checking if a user has a capability is performed by the current_user_can<\/code> function. Each user of a WordPress site might have some permissions but not others, depending on their\u00a0role. For example, users who have the Author role usually have permission to edit their own posts (the \u201cedit_posts\u201d capability), but not permission to edit other users\u2019 posts (the \u201cedit_others_posts\u201d capability).<\/span><\/span><\/span>. The client-side pipeline supports modern formats (AVIF, WebP, HEIC, UltraHDR, JPEG XL), offering better compression, and more consistent resizing quality regardless of hosting environment. It also reduces CPU and memory load on the server during image uploads<\/em> by offloading the work to capable devices.<\/p>\n\n\n\n

The feature graduated from a GutenbergGutenberg<\/span> The Gutenberg project is the new Editor Interface for WordPress. The editor improves the process and experience of creating new content, making writing rich content much simpler. It uses \u2018blocks\u2019 to add richness rather than shortcodes, custom HTML etc.\rhttps:\/\/wordpress.org\/gutenberg\/<\/a><\/span><\/span><\/span> experiment to a coreCore<\/span> Core is the set of software required to run WordPress. The Core Development Team builds WordPress.<\/span><\/span><\/span> Gutenberg feature during the 7.0 cycle and is now targeting WordPress 7.1<\/strong> as a core capabilitycapability<\/span> A\u00a0capability<\/strong>\u00a0is permission to perform one or more types of task. Checking if a user has a capability is performed by the current_user_can<\/code> function. Each user of a WordPress site might have some permissions but not others, depending on their\u00a0role. For example, users who have the Author role usually have permission to edit their own posts (the \u201cedit_posts\u201d capability), but not permission to edit other users\u2019 posts (the \u201cedit_others_posts\u201d capability).<\/span><\/span><\/span>. <\/p>\n\n\n\n

With 7.1 on the horizon, the feature could use testing to help us shake out bugs, validate performance on real content and devices, and stress-test the new capabilities.<\/p>\n\n\n\n

Tracking issues:<\/strong><\/h3>\n\n\n\n

#76756 \u2014 Client Side Media iteration for WordPress 7.1<\/a><\/p>\n\n\n\n

#74333 \u2014 Client Side Media iteration for WordPress 7.0<\/a> (previous cycle, closed)<\/p>\n\n\n\n

What\u2019s included in this round of testing<\/strong><\/h2>\n\n\n\n

The 7.1 iteration tracked in #76756<\/a> builds on the 7.0 groundwork and adds several new capabilities. Highlights include improved format support, error handling and upload resilience. <\/p>\n\n\n\n

A note on bundle size<\/h3>\n\n\n\n

Download weight and the lack of new capabilities was the biggest piece of feedback during the 7.0 cycle, so it has been a focus this iteration. Client-side processing now\u00a0exceeds<\/em>\u00a0the format and quality capabilities of the best server-side setups, while loading less ahead of time than the 7.0 prototype<\/p>\n\n\n\n