HTML5 | Unclosed Tag Checker Tool

Note: When some tags are not closed properly, it may lead to a snowball effect where it shows that many tags are not closed, most of the time, the culprit is located in the lower half of the error list, middle, or after the last element in the error list, and fixing the unclosed tags(s) would result in the whole document passing the check (assuming the provided input is a valid HTML5 code). If the code is long, sometimes it might help to split it into smaller chunks, to narrow down the tags that are not closed.

Streamline your HTML coding with our cutting-edge tool that effortlessly detects unclosed tags, ensuring your code remains error-free and your web pages display perfectly. Paste your code in the area above to find out if there are any unclosed HTML5 tags.

HTML5 is the latest standard of Hypertext Markup Language, offering advanced features and capabilities for building modern web content.

Maintaining error-free HTML code with properly closed tags is crucial for robust SEO performance, enhancing website accessibility, and ensuring seamless user experiences.


HTML features both self-closed tags for concise elements like images ('<img>') and regular tags that enclose content, such as paragraphs ('<p>'), providing versatile ways to structure web content.

Self-closed Tags

  • '<area />': Defines a clickable area within an image map.
  • '<base />': Specifies a base URL for relative URLs in a document.
  • '<br />': Inserts a line break within text or content.
  • '<circle />': Defines a circle path within SVG (Scalable Vector Graphics).
  • '<col />': Specifies column properties for HTML tables.
  • '<embed />': Embeds external content, like multimedia or plugins.
  • '<hr />': Creates a thematic break or horizontal line.
  • '<img />': Embeds an image into the document.
  • '<input />': Defines a user input element.
  • '<link />': Links external resources like stylesheets or icons.
  • '<meta />': Provides metadata about the document.
  • '<param />': Specifies parameters for plugins within object elements.
  • '<path />': Defines a vector path within SVG (Scalable Vector Graphics).
  • '<source />': Specifies multiple media resources for multimedia elements.
  • '<track />': Provides text tracks for media elements like '<video>' or '<audio>'.
  • '<wbr />': Defines a word break opportunity within the text.
  • '<command />': Defines a command button within a menu.
  • '<keygen />': Generates key-pair for forms used in cryptography.
  • '<menuitem />': Defines an item within a '<menu>'.
  • '<frame />': Defines a subwindow (deprecated in HTML5).

Regular Tags

  • '<p>': Defines a paragraph.
  • '<h1> to <h6>': Headings of different levels.
  • '<strong>': Represents strong importance.
  • '<em>': Represents emphasized text.
  • '<mark>': Highlights text for reference.
  • '<abbr>': Defines an abbreviation.
  • '<blockquote>': Represents a block quotation.
  • '<ul>': Defines an unordered list.
  • '<ol>': Defines an ordered list.
  • '<li>': Represents a list item.
  • '<dl>': Defines a description list.
  • '<dt>': Represents a term in a description list.
  • '<dd>': Represents a description in a description list.
  • '<a>': Defines a hyperlink.
  • '<nav>': Represents navigation links.
  • '<audio>': Embeds audio content.
  • '<video>': Embeds video content.
  • '<form>': Defines an HTML form.
  • '<textarea>': Creates a multi-line text input.
  • '<select>': Creates a dropdown list.
  • '<button>': Defines a clickable button.
  • '<table>': Defines an HTML table.
  • '<thead>': Defines the header of a table.
  • '<tbody>': Defines the body content of a table.
  • '<tr>': Defines a table row.
  • '<th>': Defines a table header cell.
  • '<td>': Defines a table data cell.
  • '<caption>': Provides a caption for a table.
  • '<div>': Defines a generic container.
  • '<span>': Defines inline-styled text.
  • '<header>': Represents a document or section header.
  • '<footer>': Represents a document or section footer.
  • '<section>': Represents a thematic grouping of content.
  • '<article>': Represents a standalone piece of content.
  • '<aside>': Represents content tangentially related to the surrounding content.
  • '<button>': Defines a clickable button.
  • '<details>': Represents a disclosure widget.
  • '<summary>': Provides a summary for a '<details>' element.
  • '<object>': Embeds external content or resources.
  • '<iframe>': Embeds a nested browsing context.
  • '<canvas>': Embeds graphics via scripting.
  • '<svg>': Embeds Scalable Vector Graphics.
  • '<math>': Embeds mathematical equations.
  • '<time>': Represents a specific time or range.
  • '<address>': Represents contact information.
  • '<code>': Represents computer code text.
  • '<pre>': Represents preformatted text.
  • '<fieldset>': Groups related form elements.
  • '<legend>': Provides a caption for a '<fieldset>'.
  • '<ruby>': Represents annotations for East Asian typography.
  • '<rt>': Represents pronunciation for characters in a '<ruby>' element.

Note that the lists above only include some of the common self-closing and non-self-closing (regular) HTML tags, but there are many more tags available in HTML5 for various purposes.


  • Verify HTML Code for Unclosed Tags: The button that runs the checking process.
  • Line: The text preceding the line number(s), where the tag(s) that do not have closing counterparts were detected.
  • No unclosed tags were detected.: The message when all the HTML tags are closed correctly.
  • Paste your HTML code here...: The area where the HTML code goes, for checking the unclosed/missing tags.
  • The following tag doesn't seem to be closed: In case there is one unclosed tag in the code.
  • The following tags don't seem to be closed: In case there are two or more unclosed tags in the code.


Properly closing HTML tags is of paramount importance in web development. Each tag serves as a crucial instruction for browsers to interpret and render content accurately. Neglecting to close tags can lead to unintended layout issues, misinterpretation of content, and inconsistent user experiences across different devices and browsers. This meticulous attention to detail not only ensures a seamless and visually pleasing user interface but also supports accessibility and search engine optimization. By adhering to the best practice of closing HTML tags, developers safeguard the integrity of their code, fostering reliable, accessible, and user-friendly websites that effectively convey information while maintaining a consistent visual presentation.

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