Fahad Alduraibi

Do you write posts in different languages that have different directions? 
This plugin enables a feature in the post editor which allow writing texts in Left-to-Right and Right-to-Left directions in the same post (or page) so you can write in English (and any other LTR language) and also RTL languages like Arabic, Persian and Hebrew.
Simply look for the new buttons added to the post editor after installing the plugin. (See the screenshots for better understanding)
اضافة زرارين لشريط التحرير لتمكين تحويل النص للقراءة من اليمين لليسار مثل اللغة العربية والفارسية والعبرية
<a href="http://www.fadvisor.net/blog/2008/10/wp-rtl/" rel="nofollow ugc">More details</a>
<ul>
<li>Note: This plugin will not change the direction of the post title, since that is controlled by the theme.</li>
</ul>

WP-RTL

Adds two buttons to the TinyMCE editor to enable writing text in Left to Right (LTR) and Right to Left (RTL) directions.

Arab Spell Checker Team

Enables Arabic Spell Checking in the TinyMCE editor. 
The plugin relies on our spell checking API server to check words and generate suggestions. For that a single API request is done, and the response will contain all the presumably misspelled words and their correction suggestions. The plugin also uses an API endpoint to check the validity of the API keys used for spell checking. No other info is sent or exchanged with the API.
This plugin relies on Classic Editor plugin (https://wordpress.org/plugins/classic-editor/) and must be installed before enabling this plugin.
Service website (In Arabic only): https://arabicspellchecker.com/ 
Service’s Terms of use link (In Arabic only) : https://arabicspellchecker.com/terms.html

WP-SARAHSPELL

Enables Arabic Spell Checking in the TinyMCE editor.

WP-RTL vs WP-SARAHSPELL