Securely encode HTML code to prevent execution or decode encoded HTML back to its original form. Protect your web content from script injection and cross-site scripting (XSS) attacks.
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HTML encoding and decoding are essential processes in web development that convert special characters in HTML to their corresponding HTML entities and vice versa. This ensures that text displays correctly in web browsers and prevents security vulnerabilities.
HTML encoding replaces reserved characters with HTML entities that begin with an ampersand (&) and end with a semicolon (;). For example:
The encoder scans the HTML content to identify characters that have special meaning in HTML, such as <, >, &, ", and '.
Each special character is replaced with its corresponding HTML entity, either by name (like <) or by numeric code (like <).
Regular text and characters that don't require encoding remain unchanged to maintain readability and functionality.
The encoded output can now be safely displayed in browsers without risk of script execution or rendering issues.
| Character | Entity Name | Entity Number | Description |
|---|---|---|---|
| < | < | < | Less than |
| > | > | > | Greater than |
| & | & | & | Ampersand |
| " | " | " | Double quotation mark |
| ' | ' | ' | Apostrophe |
| © | © | © | Copyright symbol |
| ® | ® | ® | Registered trademark |
| € | € | € | Euro currency symbol |
Encode user inputs to prevent XSS attacks and malicious script injection in web applications.
Properly encode HTML content in CMS systems to ensure correct display and prevent code conflicts.
Encode HTML when sending data between systems to maintain data integrity and prevent parsing errors.
Display HTML code examples on web pages by encoding the code to prevent browser interpretation.
Ensure HTML emails render correctly across different email clients by properly encoding special characters.
Handle HTML content in API responses and requests by properly encoding and decoding data.
| Aspect | HTML Encoding | URL Encoding |
|---|---|---|
| Purpose | Display HTML safely in browsers | Encode data for URLs and HTTP requests |
| Format | &entityname; or &#number; | %hexadecimal (e.g., %20 for space) |
| Common Use | Web page content, form data | URL parameters, query strings |
| Key Characters | <, >, &, ", ' | Spaces, &, ?, =, /, : |
HTML Encoding: Use when displaying user-generated content on web pages, showing code examples, or preventing XSS attacks.
URL Encoding: Use when passing data in URLs, submitting form data via GET method, or working with API endpoints.
HTML encoding and HTML escaping are often used interchangeably, but technically, encoding refers to converting characters to HTML entities, while escaping refers to the broader process of making text safe for HTML contexts, which may include encoding as well as other security measures.
Yes, it's a critical security practice to encode all user inputs before displaying them on your website. This prevents XSS attacks where malicious scripts could be injected through user-provided content. However, the encoding should be context-specific - HTML encoding for HTML content, JavaScript encoding for JavaScript contexts, etc.
Proper HTML encoding generally doesn't negatively impact SEO. In fact, it can help by ensuring your content displays correctly across different browsers and devices. However, excessive or incorrect encoding might make content harder for search engines to parse. Always use encoding appropriately and validate your HTML.
HTML decoding is necessary when you need to convert encoded HTML entities back to their original characters. Common scenarios include: processing user inputs that were previously encoded, displaying encoded content in non-HTML contexts, or when working with data that needs to be manipulated programmatically.
Regular alphanumeric characters (A-Z, a-z, 0-9) and most common punctuation don't need encoding. The primary characters that should be encoded are: <, >, &, ", and '. Additionally, characters outside the standard ASCII range might need encoding depending on your character encoding settings.
Named entities use descriptive names (like < for <) while numeric entities use character codes (like < for <). Named entities are more readable but not all characters have named equivalents. Numeric entities work for all Unicode characters and are more universally supported.