Bjørn Johansen

This is a WordPressified version of the excellent, lightweight (for real!) imageLightbox.js (MIT-licensed) by Osvaldas Valutis (http://osvaldas.info/image-lightbox-responsive-touch-friendly)
This is his introduction to the lightbox: 
“As for the image lightboxes, I have always lacked simplicity for them. I mean not only the visual design, but the overall experience: from implementation to UX. All due respect, but I have never liked any of these light-fancy-face-boxes. They all were solving problems that just don’t exist: lots of unwanted features by default, total mess in markup, no native behavior for touch screens. I was working on a project and needed an image lightbox that solves these problems. I needed a lightbox only for images, not video, text, and iframes at once. I made ImageLightbox.js.”
This version autodetects all links to image files and opens them in the lightbox.
For your “install, activate and go”-convenience, this plugin comes with a minimal CSS that easily can be deactivated and/or replaced.
The plugin can also be themed to your liking. An example theme is available here: https://github.com/bjornjohansen/imagelightbox-theme-smooth
Please let me know if you have any issues. Fastest way to get a response is by Twitter: https://twitter.com/bjornjohansen

imageLightbox

Image Lightbox, Responsive and Touch‑friendly.

f13dev

Each image within a post or page will become a clickable link with a popup lightbox. This does not use an off the shelf lightbox, instead a custom made 6KB jQuery lightbox helping to reduce overhead on your site without compormising features.
This lightbox is fully acessible via keyboard only input, meets and exceeds WCAG AA contrast requirements, includes keypress navigation (arrow keys to navigate between images and escape to close).
No configuration is required to enable the Lightbox once installed and activated on your WordPress site. Should you wish to exclude an image from the lightbox, simply add the class “no-lightbox” to the image.
<a href="https://f13.dev/wordpress-plugin-lightbox/" rel="nofollow ugc">Read more about F13 Lightbox</a>
[https://f13.dev/wp-content/uploads/2021/10/f13-lightbox-example.png Example of F13 Lightbox]

F13 Lightbox

Add a lightbox for any image within a post or page, includes accessibility features.

imageLightbox vs F13 Lightbox