mattdu

This plugin uses the custom taxonomy features of WordPress to create “bylines” — essentially, tags representing authors who contributed to a post. The differentiating feature of this plugin is that it should not require any modifications to your theme files (assuming it is already displaying the post author).
This plugin would be useful for publishing situations where the majority of your content is from contributors who you don’t necessarily want to have access to your back-end. It still conveys the appearance that the authors are members of the site (it provides a built-in archive page for each Byline). If your theme displays tag descriptions, you could use the Byline description field to identify guests vs. “staff” writers or provide other author information.
You can see an example of this plugin at work at http://thedailycougar.com

Byline

The Byline plugin is simple and suitable for multi-author WordPress sites.

Best For Multi Author

Solves the co/multi-author problem without modifying the theme. Uses a custom taxonomy, "Byline," that replaces the Display Author.

Automattic

Daniel Bachhuber

Gary Jones

Mohammad Jangda

Assign multiple bylines to posts, pages, and custom post types via a search-as-you-type input box. Co-authored posts appear on a co-author’s archive page and in their feed. Co-authors may edit the posts they are associated with, and co-authors who are contributors may only edit posts if they have not been published (as is core behavior).
Add writers as bylines without creating WordPress user accounts. Simply <a href="https://github.com/Automattic/Co-Authors-Plus/wiki/Creating-and-editing-guest-authors" rel="nofollow ugc">create a guest author profile</a> for the writer and assign the byline as you normally would.
On the frontend, use the <a href="https://github.com/Automattic/Co-Authors-Plus/wiki/Template-tags" rel="nofollow ugc">Co-Authors Plus template tags</a> or the <a href="https://github.com/Automattic/Co-Authors-Plus/wiki/Blocks" rel="nofollow ugc">block editor blocks</a> to list co-authors anywhere you’d normally list the author.
<h3>Documentation</h3>
<ul>
<li>Usage — themer and site-owner guides live on the <a href="https://github.com/Automattic/Co-Authors-Plus/wiki" rel="nofollow ugc">GitHub Wiki</a>: template tags, blocks, guest author management, and multisite.</li>
<li>Developer reference — lives in-repo under <a href="./docs/" rel="nofollow ugc"><code>docs/</code></a> (not bundled in the distribution ZIP):
<ul>
<li><a href="./docs/filters.md" rel="nofollow ugc">Filters and actions</a></li>
<li><a href="./docs/rest-api.md" rel="nofollow ugc">REST API</a></li>
<li><a href="./docs/upgrading-to-4.0.md" rel="nofollow ugc">Upgrading to 4.0</a></li>
</ul>
</li>
</ul>
Co-Authors Plus is an almost complete rewrite of the <a href="https://wordpress.org/plugins/co-authors/" rel="ugc">Co-Authors</a> plugin originally developed by Weston Ruter (2007). The original plugin was inspired by the ‘<a href="https://txfx.net/2005/08/16/new-plugin-multiple-authors/" rel="nofollow ugc">Multiple Authors</a>‘ plugin by Mark Jaquith (2005).

Co-Authors Plus

No support at all , also it doesn't work with wpml

No Support - Not compatible with WPML

Not working

Works!

I rarely ever give 1 star reviews, but developers who take over a plugin - making a breaking change that took a while to resolve - and then refuse to follow standard practice by providing a changelog (despite requests) for future updates, cannot be trusted.

Avoid at all costs.

Cannot trust developers

Assign multiple bylines to posts, pages, and custom post types with a search-as-you-type input box.

Byline vs Co-Authors Plus