Bhagirath Dhanani

Allow to display comment form inside post, page and widget.
Basically comment is inbuilt feature in WordPress but in some case we need embedded comment form.
Example.
* we need to embedded comment inside post.
* some theme build without comment form for pages or custom post type.
* you want to display comment form for specific post only, so you can disable comment for all page and use shortcode to display comment.
* in custom development you need comment form inside widget.
so here we have comment form shortcode to display comment using shortcode inside post,page or widget.
Comment Form Shortcode Help
You can use below ShortCode in post or page or in widget to show comment form.
[comment comment_file =”/comments.php”]
Here comment_file is optional, if you have custom comment file, you have to pass here.
How To Use : 
[comment]
[comment comment_file =”/short-comments.php”]

Comment Form Shortcode

Denis Yanchevskiy

DCO Comment Attachment allows your visitors to attach images, videos, audios, documents and other files with their comments. They will also be able to automatically embed links from Youtube, Facebook, Twitter and other services in the comment text.
With plugin settings you can:
<ul>
<li>Limit the maximum file upload size.</li>
<li>Make an attachment required.</li>
<li>Specify whether the attachment will be embedded or displayed as a link.</li>
<li>Enable/Disable autoembed links (like Youtube, Facebook, Twitter, etc.) in the comment text.</li>
<li>Select an attachment image size from thumbnails available in your WordPress install.</li>
<li>Link a thumbnail to a full-size image with lightbox plugins support (see <a href="#faq" rel="nofollow ugc">FAQ</a> for details).</li>
<li>Open a full-size image in a new tab or link thumbnail to the attachment page.</li>
<li>Enable/Disable multiple upload.</li>
<li>Combine images to gallery.</li>
<li>Select an attachment image size for the images gallery.</li>
<li>Restrict attachment file types.</li>
<li>Decide who will be able to upload attachments: all users or only logged users.</li>
<li>Manually moderate comments with attachments.</li>
</ul>
You can also:
<ul>
<li>Add, replace or delete an attachment from a comment on the Edit Comment screen.</li>
<li>Attach an unlimited number of attachments to the comment in the admin panel.</li>
<li>Delete an attachment from a specific comment or bulk delete attachments from comments on the Comments screen.</li>
<li>Display attachments attached to comments to the current post (or a specific post) with the <code>[dco_ca]</code> shortcode. You can also filter by type. See <a href="#faq" rel="nofollow ugc">FAQ</a> for details.</li>
</ul>
Attachments are uploaded to the WordPress Media Library and deleted along with the comment (if this is set in the settings).
REST API is supported.
DCO Comment Attachment is also available on <a href="https://github.com/yadenis/DCO-Comment-Attachment" rel="nofollow ugc">GitHub</a>.

DCO Comment Attachment

Allows your visitors to attach files with their comments

Comment Form Shortcode vs DCO Comment Attachment