There are several character counter online tools available, each with their own set of pros and cons. Here are some of the most popular options:  

Free Character Counter

1. CharacterCountTool.com
   Pros:

• Simple and easy to use interface
• Counts characters, words, and sentences accurately
• Supports multiple languages
• Provides a character count for both plain text and HTML content
  Cons:
• Limited features compared to other tools on this list  

  Twitter Character Counter

2. WordCounter.net
   Pros:

• Offers a range of features including word count, character count, and reading level analysis
• Supports multiple languages
• Easy to use interface
  Cons:
• May not be as accurate as some other tools for very long documents or complex content

3. CharacterCount.org
   Pros:

• Accurate character counting for both plain text and HTML content
• Supports multiple languages
• Offers additional features such as keyword density analysis and readability statistics
  Cons:
• Interface may be less intuitive than some other tools

4. Online-Utilities.com
   Pros:

• Offers a wide range of tools in addition to character counting, including password generators and hash calculators
• Accurate character counting for both plain text and HTML content
• User-friendly interface
  Cons:
• Some users have reported issues with the accuracy of certain tools on this site

5. SEOChat.com
   Pros:

• Includes a range of SEO tools in addition to character counting, including keyword research and backlink checkers
• Accurate character counting for both plain text and HTML content
• User-friendly interface
  Cons:
• Some users have reported issues with the accuracy of certain tools on this site

6. WebPageAnalysis.com
   Pros:

• Offers a comprehensive set of web page analysis tools, including character counting, keyword density analysis, and link analysis
• Accurate character counting for both plain text and HTML content
• User-friendly interface
  Cons:
• Some users have reported issues with the accuracy of certain tools on this site

7. Mozilla Add-ons
   Pros:

• Offers a variety of add-ons that include character counting functionality, such as the "Character Count" add-on
• Can be used directly within Firefox browser
• Often more convenient than using an external website
  Cons:
• Requires installation of an add-on
• May not be as accurate as dedicated online tools

8. Google Doc's built-in tool
   Pros:

• Convenient option for those who already use Google Docs regularly
• Accurate character counting for both plain text and formatted content
• No need to install any additional software or extensions
  Cons:
• Only works within Google Docs
• Not suitable for non-Google Docs users

9. Microsoft Word's built-in tool
   Pros:

• Convenient option for those who already use Microsoft Word regularly
• Accurate character counting for both plain text and formatted content
• No need to install any additional software or extensions
  Cons:
• Only works within Microsoft Word
• Not suitable for non-Microsoft Word users

Ultimately, the best character counter online tool will depend on your specific needs and preferences. If you require a simple and user-friendly solution, CharacterCountTool.com or WordCounter.net may be good options. For more advanced features and analysis, consider using CharacterCount.org or one of the other multi-tool websites like Online-Utilities.com or SEOChat.com.