hidekazu-konishi.com

HTML Entity Encoder Decoder Tool - Encode Decode and Reference HTML Special Characters

First Published: 2026-04-01
Last Updated: 2026-04-01

Free HTML Entity Encoder and Decoder with three encoding formats (named, decimal, hex), three scope modes (safe minimum, all special characters, full non-ASCII), character analysis, and a comprehensive searchable reference table of 250+ HTML entities. All processing is performed entirely within your browser — your data never leaves your device.

Features:

• Three Encoding Formats: Named entities (&), Decimal numeric references (&), and Hexadecimal numeric references (&).
• Three Encoding Scopes: Safe Minimum (only the 5 characters that must be escaped in HTML), All Special Characters (all characters with named HTML entities), and Full Non-ASCII (every non-ASCII character).
• Universal Decoder: Decodes all entity types — named, decimal, and hex — simultaneously using the browser's built-in HTML parser.
• Character Analysis Panel: After encoding, see a detailed breakdown of every converted character with its Unicode codepoint and resulting entity.
• Smart Paste Detection: Automatically detects HTML entities when text is pasted into the decode field and offers a one-click decode.
• Comprehensive Entity Reference: Searchable, filterable table of 250+ standard HTML entities organized by category (Basic HTML, Latin Extended, Mathematical, Greek, Currency, Arrows, Punctuation).
• 100% Client-Side: All processing happens in your browser. No data is sent to any server. Works offline once loaded.

How to Use:

1. Encode: Enter plain text in the left "Plain Text" area, select your preferred Encoding Format and Scope, then click "Encode →".
2. Decode: Paste HTML containing entities in the right "Encoded Text" area, then click "← Decode".
3. Smart Decode: Paste encoded HTML into the right textarea — a banner will appear offering to auto-decode immediately.
4. Character Analysis: After encoding, click the "Character Analysis" panel to see which characters were converted and their entity representations.
5. Copy Result: Click "Copy Result" to copy the most recent output (encode result or decode result) to your clipboard.
6. Search Reference: Scroll down to the HTML Entity Reference Table and use the search box or category filter to find specific entities.

Important Notes:

• The "Safe Minimum" scope encodes only <, >, &, ", and ' — the five characters that must always be escaped in HTML content and attributes.
• Named entity output will fall back to decimal numeric references for characters that have no standard named entity (e.g., in Full Non-ASCII mode for CJK characters).
• The decoder uses the browser's native HTML parser, which correctly handles all valid entity formats including named, decimal, and hexadecimal references.
• Encoding format and scope options only affect the Encode operation. Decoding always handles all entity types regardless of these settings.
• The entity reference table below includes all W3C-standardized HTML named entities for quick lookup.