Abrar Ahmed

This plugin is particularly designed for developers so that they can easily upload images via URL.
Features of this plugin: 
1. You can give URL to this plugin then this will upload the image to WP and will return attachment ID. 
2. You can give the same URL multiple times but it will not upload an image each time, it will upload an image once and will return attachment ID each time when it is called. 
3. If image URL is change or size of the image on URL is different then just on that condition image will be uploaded to WordPress
It has some more functions too that will help developers for getting details about image and size as well.
<h3>Arbitrary section</h3>
The following features of this plugin are going to be defined for developer understandings.
<h3>A brief Markdown Example</h3>
Unordered list:
<ul>
<li>Function iUploadImageByURL This function is the basic function that can be used while upload image from URL. It will return Attachment_ID after creating an attachment from image URL. Image from URL will be uploaded once if URL and size of the image are same. If the same URL with the same size of the image given then already created attachment of that image will be uploaded.</li>
<li>Function iGetFileSize This function can be used to get the size of the image from URL.</li>
<li>Function sFormatSize This function will return measurement format size of the image.</li>
</ul>

URL Image Uploader

This function is a tool for developers to help them upload images from URL to the WordPress site.

sh1zen

This is an advanced upload plugin for those who need a little more than the default multi file upload of Gravity Forms.
The plugin options page provides you with granular control over many Plupload parameters from file extension filters to chunked uploading and runtimes.
All files are uploaded to the WordPress media library on successful form submission making for easy access and management.
FEATURES
<ul>
<li>Safety: validation of both file extension and mime type.</li>
<li>Privacy: filenames changed once added to media library.</li>
<li>Advanced Customization: many options and many hooks to modify any plugin rule.</li>
<li>Large File Support: enabled by chunked file uploads.</li>
<li>Media library integration: all files are uploaded to the WordPress media library on successful form submission making for easy access and management.</li>
<li>Entry list creation integration: A list of all correctly uploaded files, with relative link.</li>
</ul>
DONATIONS
This plugin is free and always will be, but if you are feeling generous and want to show your support, you can buy me a 
beer or coffee <a href="https://www.paypal.com/donate?business=dev.sh1zen%40outlook.it&item_name=Thank+you+in+advanced+for+the+kind+donations.+You+will+sustain+me+developing+GF-Multi-Uploader.&currency_code=EUR" rel="nofollow ugc">here</a>, I will really appreciate it.
<h3>Hooks</h3>
Filters: 
* ‘gfmu_plugin_locale’ 
* ‘gfmu_before_attach_uploads’ 
* ‘gfmu_maybe_insert_attachment’ 
* ‘gfmu_server_validation_args’ 
* ‘gfmu_insert_attachment_args’ 
* ‘gfmu_field_options’ 
* ‘gfmu_save_entry’

Multi Uploader for Gravity Forms

Chunked Multiple file uploads, from images, videos to pdf. Files stored in WP Media Library.

URL Image Uploader vs Multi Uploader for Gravity Forms