There are ways to let the user resize images, at least, when they selected them and just before uploading them, but this depends on the client side library you use to handle uploads for now I am handling this server side. I cannot expect users to always prepare and optimise images prior to uploading, so I have added a little processing on upload to both resize and improve compression of the uploaded images for use with the web. The problem I am facing with so many features requiring image uploads is that the user might upload images that are too large for their purpose or unoptimised in terms of compression and other qualities, resulting in worse performance for the end user (larger files take longer to download and render) as well as increased storage and bandwidth costs.

DynaBlogger is a Rails app, so for this I use ActiveStorage, which is quickly becoming the standard way of handling uploads in Rails since it's built in the framework and doesn't require additional dependencies or even database migrations for models that require attachments, making things simpler than with other solutions provided that you stick to ActiveStorage's conventions. There are user uploads in the app for other things but the above are specifically for images.

logo/favicon/cover/twitter/facebook images for the blog.

featured/cover/twitter/facebook images for posts and pages.

My recently launched blogging platform DynaBlogger allows users to upload images in a number of places:

Javascript resize image client side