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Automatically upload external images To media Library and replaces in post
This is simple plugin. 
If you need a plugin or custom theme, I am at your service through the following communication methods : (non-free) 
Telegram : @MostafaShiraali 
Discord : MostafaShiraali#7754

Simple Image Uploader

Automatically upload external images To media Library and replaces  in post

imanabuhaydari

Iman Heydari

This plugin functionality happens when you want to save a new post, it searches for external image links, and uploads them into your site, then attaches the images to the post. 
This plugin is so light and has been written with the least codes, So it does not decline your site speed.
You can set the first image as a thumbnail, while uploading.( Please turn on the related switch in settings page )

Automatic Image Uploader

A useful and simple plugin

The plugin works, but version 1.3.1 has drawbacks: 
1) The unloading process breaks down when phrases like "$70/month" are found in the post text (wp_extract_urls sees this as a url, processing $urls causes an exception). 
2) Does not work correctly with urls having parameters.

The plugin is wonderful, but needs to be improved

This plugin search for images in the content of posts and upload it automatically.

Simple Image Uploader vs Automatic Image Uploader