Jampack is a post-processing tool designed to optimize static websites for the best user experience and superior Core Web Vitals scores. Unlike bundlers or frameworks, Jampack enhances the output of Static Site Generators (SSGs) by focusing on performance and efficiency.
Jampack automates the transformation of regular images into responsive formats, including WebP and AVIF, ensuring that images are appropriately sized for various devices and screen resolutions. It also optimizes images hosted on CDNs by making them responsive and can download and optimize external images for better performance.
The tool prioritizes assets based on their placement on the page. Above-the-fold assets are loaded with higher priority, and small images are embedded directly into the HTML to speed up rendering. Below-the-fold assets, such as images and iframes, are lazy-loaded to improve initial load times.
Critical CSS is inlined to avoid Flash of Unstyled Content (FOUC), with the rest of the CSS being lazy-loaded. Jampack also prefetches links to speed up future page navigations dynamically as they enter the viewport, thanks to the integration with quicklink.
In its second pass, Jampack compresses all untouched assets while maintaining their original names and formats. Various file types are compressed using specific tools like html-minifier-terser for HTML, lightningCSS for CSS, esbuild or swc for JavaScript, svgo for SVG, and sharp for image formats like JPEG, PNG, WebP, and AVIF.
Jampack is used by several websites, including those of ‹div›RIOTS, keycloak.ch, bayjs.org, and others, demonstrating its effectiveness in real-world applications. The tool is released under the MIT license and is part of the open-source community.
Pricing
Pricing information is not available