HTML Codec

Freely convert between Text and HTML Entities

HTML Codec is a free online tool for easy conversion between HTML special characters and HTML entities. Convert special characters like "<", ">", "&", "\"" to HTML entities like "<", ">", "&", """ and vice versa. Your input data is not stored on the server, so you can safely convert sensitive information.

How to Use

Using the HTML Codec is very simple:

Step 1: Enter Data and Select Input Format
Enter the data you want to convert in the text box below. Select the input format (Text or HTML Entities).
Step 2: Select Output Format
Choose the conversion destination format. You can select from Text (special characters) or HTML Entities.
Step 3: Click Convert Button
Click the "Convert" button and the entered data will be instantly converted to the selected format. Copy the result and use it.

Your input data is not stored on the server. All processing is completed in the browser, and your privacy is completely protected.

HTML Conversion Tool

Input Format

Output Format

Enter Data to Convert

Conversion Result

Practical Use Cases for HTML Codec

HTML Codec is used in the following situations in web development and content creation:

Creating Email Templates

Safely display text containing special characters in HTML email templates. Correctly displays symbols and quotation marks while maintaining email client compatibility.

Generating Data URLs (Data URIs)

When embedding small images or icons directly in HTML or CSS, Base64-encoded Data URLs are used. This reduces HTTP requests and improves page loading speed.

API Authentication (Basic Auth)

In HTTP Basic authentication, the username and password are combined with a colon (:) and Base64 encoded for inclusion in the authentication header.

JSON Web Token (JWT)

The header and payload sections of a JWT are represented using Base64URL encoding (a variant of Base64).

Transferring Binary Data

When transferring binary data in JSON format, Base64 encoding is used to convert it to text format.

What are HTML Entities? Understanding Special Character Escaping

Base64 is an encoding method that represents binary data using only 64 printable ASCII characters. The name "64" comes from the fact that it uses 64 characters (2 to the 6th power).

The 64 Characters Used in Base64

Uppercase alphabet: A-Z (26 characters)
Lowercase alphabet: a-z (26 characters)
Numbers: 0-9 (10 characters)
Symbols: + (plus) and / (slash) (2 characters)
Padding character: = (equals)

How Encoding Works

Base64 encoding divides 3 bytes (24 bits) of data into four 6-bit units, mapping each to one of the above 64 characters.

Encoding Example

Original text: "Hello"
Binary representation: 01001000 01100101 01101100 01101100 01101111
Base64 result: SGVsbG8=

When the data size is not a multiple of 3, padding with "=" is added at the end.

Uses and Benefits of Base64 Encoding

Improved Data Transfer Reliability

Even in systems that only support text (such as older email systems), binary data can be safely transferred using Base64 encoding. It prevents data corruption.

Cross-Platform Compatibility

Since Base64 uses only ASCII characters, there are no character encoding issues when exchanging data between different systems.

Conversion to URL-Safe Strings

Using Base64URL encoding (replacing + with - and / with _) allows you to generate strings that can be safely used in URLs and filenames.

Embedding Data

By embedding images and fonts directly in CSS and HTML files, you can reduce requests to external files and improve page performance.

Important: Base64 is NOT Encryption

⚠️ Base64 encoding is NOT encryption. This is an important distinction.

Difference Between Encoding and Encryption

Encoding

Process of converting data to another format
Anyone can reverse it (reversible)
Not for security purposes
Base64 encoding falls into this category

Encryption

Converting data to unreadable format using a secret key
Cannot be reversed without the key
Purpose is security and privacy protection
Examples include AES, RSA, etc.

Base64-encoded strings can be easily decoded by anyone. Therefore, you should never use Base64 to "hide" passwords or confidential information.

Proper Usage

✅ Converting data transfer formats
✅ Text representation of binary data
✅ Encoding email attachments
❌ Protecting passwords (use encryption instead)
❌ Hiding confidential information (use encryption instead)

If you need to protect confidential data, use strong encryption algorithms such as AES-256.

Frequently Asked Questions (FAQ)

Are HTML encoding and HTML escaping the same?

Yes, they basically mean the same thing. Both refer to converting HTML special characters to HTML entities. "Escaping" is a general programming term, while "encoding" is used from the character conversion perspective.

Which characters need to be converted to entities?

At minimum, the five characters <, >, &, ", and ' should be converted to entities. Especially < and > are required as they are interpreted as HTML tags. When displaying user input, all special characters should be converted to entities to prevent XSS attacks.

What is the difference between numeric entities and named entities?

Numeric entities (<) are represented by Unicode character codes and can be used for all characters. Named entities (<) are represented by readable names but are limited to about 2,000 types defined in HTML5. Both function the same way.

What are ENT_QUOTES and ENT_HTML5?

They are flags for PHP's htmlentities() function. ENT_QUOTES encodes both single and double quotes, and ENT_HTML5 uses the HTML5-compliant entity set. This tool combines both for the safest conversion.

Are multibyte characters like Japanese also converted to entities?

No, multibyte characters like Japanese that are correctly encoded in UTF-8 can be displayed as-is in HTML and do not need to be converted to entities. However, they can also be represented as numeric entities (あ = あ).

Is HTML entity conversion encryption?

No, HTML entity conversion is not encryption, but simply a change in character representation. From a security perspective, it is "escaping" to prevent XSS attacks, which is different from encryption that protects data confidentiality.

How do I perform HTML encoding in programming languages?

Each language has dedicated functions. PHP: htmlentities(), JavaScript: textContent (auto-escape), Python: html.escape(), Java: StringEscapeUtils.escapeHtml4(), Ruby: CGI.escapeHTML(), etc. are available.

What causes garbled characters even after decoding?

Character encoding (UTF-8, Shift_JIS, etc.) may not match. Also, incomplete entities (no semicolon after &lt, etc.) or multiply-encoded data (&lt; → < → < requiring two decodes) may be the cause.