4SEF is a Joomla 3 and Joomla 4 extension that offers SEF URLs creation and customization. If that sounds familiar, it's likely because this is what sh404SEF has been doing for about 15 years now and if you read this, there's a chance you've used sh404SEF at some point in your Joomla adventures!
sh404SEF however is not really capable of making the jump to Joomla 4, and it is also limited now in terms of pure SEO features.
Last year, 4SEO was released to take over all of sh404SEF SEO features and add many more. Now 4SEF is - nearly - ready to take over creating and managing SEF URLs for either Joomla 3 and Joomla 4 websites.
It's not a stripped-down version of sh404SEF, re-packaged for Joomla 4. 4SEF is using the same modern user interface that powers 4SEO, and all its code has been rewritten from scratch for better performance and some improved features, while retaining the same SEF URLs that sh404SEF produces.