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URL Encoder & Decoder Tool

This browser-based tool converts Japanese text and special characters in URLs to percent-encoding format (%XX) and vice versa. Adopts RFC 3986-compliant UTF-8 encoding, perfect for API development, search query creation, and sharing Japanese URLs. No registration required for instant use, and no data is transmitted externally.

What You Can Do

The URL Encoder & Decoder Tool converts Japanese text and special characters in URLs to safe percent-encoding format (%XX), and vice versa, all within your browser. Perfect for API development debugging, search query creation, and sharing Japanese URLs. Adopts RFC 3986-compliant UTF-8 encoding.

✅ Encode: Convert Japanese text and symbols like "検索" → "%E6%A4%9C%E7%B4%A2"
✅ Decode: Restore percent-encoded strings to original text
✅ RFC 3986 Compliant: Accurate conversion following URL standard specifications

Easily encode and decode URLs. Safely convert URLs containing Japanese text or special characters.

String to Encode

Encoded Result

String to Decode

Decoded Result

💼 Use Cases

API Development & Debugging - Properly encode URL parameters containing Japanese text or symbols
URL Sharing - Convert Japanese URLs to alphanumeric format for safe transmission
Query Parameter Creation - Convert search keywords to URL format
Browser Address Bar Analysis - Convert encoded URLs to readable format
Web Development Learning - Perfect for understanding URL encoding mechanisms

How to Use

📌 Basic Usage

Simply enter the string you want to encode or decode and click the corresponding button to execute the conversion.

💡 What is URL Encoding

URL encoding (percent-encoding) is a method to convert characters that cannot be used in URLs or reserved characters into a safe format. It is necessary when using multibyte characters like Japanese or special characters in URLs.

⚙️ Conversion Examples

Japanese: "検索" → "%E6%A4%9C%E7%B4%A2"
Space: "hello world" → "hello%20world"
Symbols: "?&=" → "%3F%26%3D"

🔍 Common Use Cases

Search Parameters: Including Japanese text in search queries
API Calls: Including special characters in URL parameters
Link Sharing: Sharing URLs containing Japanese text
Debugging: Checking the content of encoded URLs

📝 Notes

URL encoding uses UTF-8 character set
Be careful not to encode already encoded strings (double encoding)
Encode only necessary parts, not the entire URL

💼 Application Scenarios

Web API query parameter creation
Form data URL transmission
Decoding encoded URLs
Japanese URL conversion
Development and debugging work

📚 Technical Explanation of URL Encoding

📖 About RFC 3986 - Basics of URL Standards

RFC 3986 (Uniform Resource Identifier: Generic Syntax) is the official standard specification by IETF (Internet Engineering Task Force) that defines the syntax of URLs and URIs. It was published in 2005 as a revision of RFC 2396 from 1998.

🔹 Reserved Characters Defined in RFC 3986

The following characters have special meanings in URLs and must be encoded when used as data:

: Separator between scheme and host (e.g., https://)
/ Path separator (e.g., /tools/url-encoder/)
? Query string start (e.g., ?q=search)
# Fragment identifier start (e.g., #section)
[ ] @ ! $ & ' ( ) * + , ; = Subcomponent delimiters

🔹 Unreserved Characters

The following characters can be used without encoding:

Alphanumeric: A-Z a-z 0-9
Symbols: - _ . ~ (hyphen, underscore, period, tilde)

💡 This tool performs RFC 3986-compliant encoding and decoding. Reserved characters used as data are automatically converted to percent-encoding.

🔧 How Percent-Encoding Works

Percent-encoding is a technique to convert characters that cannot be used in URLs into hexadecimal ASCII code representation. The conversion is performed in the following steps:

📌 Encoding Steps (Example: "検索")

Convert to UTF-8 byte sequence
- "検" → UTF-8: E6 A4 9C (3 bytes)
- "索" → UTF-8: E7 B4 A2 (3 bytes)
Convert each byte to percent sign + hexadecimal
- E6 → %E6
- A4 → %A4
- 9C → %9C
- E7 → %E7
- B4 → %B4
- A2 → %A2
Result: "検索" → %E6%A4%9C%E7%B4%A2

📌 Decoding Steps (Reverse Conversion)

Convert hexadecimal numbers after percent signs to byte values
Interpret byte sequence as UTF-8 and restore to original string

⚠️ Warning: Re-encoding already encoded strings results in "double encoding" and cannot be decoded correctly. Example: Re-encoding %E6%A4%9C → %25E6%25A4%259C (% becomes %25)

🔤 Character Encoding and Mojibake Prevention

The most important aspect of URL encoding is unified Character Encoding. Mojibake (garbled text) occurs when different character encodings are used for encoding and decoding.

🌐 Common Character Encodings

Encoding	Description	URL Encoding
UTF-8	Current web standard. Represents all Unicode characters in 1-4 bytes	✅ Recommended (Used by this tool)
Shift_JIS	Legacy Japanese character code. 1-2 bytes	⚠️ Not recommended (compatibility issues)
EUC-JP	Japanese code used in UNIX	⚠️ Not recommended (now rare)
ISO-8859-1	For Western European languages. No Japanese support	❌ Cannot use for Japanese

🛡️ Best Practices to Prevent Mojibake

Unify with UTF-8: Match HTML <meta charset="UTF-8"> with server settings (Content-Type)
Use UTF-8 for URL encoding: All modern URL encoders including this tool adopt UTF-8
Avoid double encoding: Don't call JavaScript's encodeURIComponent() multiple times
Use same character code for decoding: Always decode UTF-8 encoded URLs with UTF-8

📌 This tool always uses UTF-8, ensuring 100% compatibility with modern web applications and APIs. Only when interacting with legacy Shift_JIS-based systems is server-side character code conversion required.

📅 📅 Last Updated:: December 9, 2025 | 💬 💬 Feedback:: Suggestions & Comments