URL Encoder & Decoder

Professional URL encoder and decoder for web developers. Handle special characters, query parameters, and URI components with percent encoding support.

URL Encoder & Decoder

Encode or decode URLs and text with support for different encoding methods

Operation

Encoding Method

Actions

Input Text

Quick Examples:

Key Features

Encode & decode URLs and text safely

Support for encodeURI and encodeURIComponent

Real-time processing with instant results

Copy results to clipboard easily

Quick access to common URL examples

Error handling for malformed input

Understanding URL Encoding

Percent Encoding: URLs use % followed by hex codes to represent special characters (e.g., space = %20)

encodeURI(): Preserves URL structure characters like :, /, ?, #, @, and [, ]

encodeURIComponent(): Encodes all special characters except letters, digits, -, _, ., !, ~, *, ', (, )

Use Cases: encodeURI for complete URLs, encodeURIComponent for query parameters and form data

Tips & Best Practices

Always Encode User Input: Prevent XSS attacks and URL structure breaking in web forms

Choose Right Method: encodeURIComponent() for query values, encodeURI() for complete URLs

Detect Double Encoding: Check for % characters to avoid encoding already-encoded strings

Validate After Decoding: Use Content Security Policy and input sanitization after decoding

Handle API Responses: Many APIs return URL-encoded data that needs proper decoding

Test International Content: Verify proper UTF-8 encoding for non-English characters

URL Length Limits: Browsers have 2048-character URL limits; consider POST for long data

Server-Side Validation: Always validate and re-encode URLs on the server side

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Frequently Asked Questions

When should I use encodeURIComponent vs encodeURI?

Use encodeURIComponent for individual URL parts like query parameters, form data, or path segments. Use encodeURI when encoding a complete URL while preserving its structure (/, :, ?, #, @).

Why do spaces become %20?

Spaces (ASCII 32) are encoded as %20 in percent encoding. The space character is not allowed in URLs according to RFC 3986, so it must be encoded as %20 (hexadecimal 20 = decimal 32).

How do I handle form data with special characters?

Always use encodeURIComponent() for form field values before building query strings. For example: "name=" + encodeURIComponent(userInput) ensures special characters like &, =, + are properly encoded.

Can I decode any URL-encoded string?

Most properly encoded strings can be decoded, but malformed encoding (like incomplete % sequences) causes errors. Always use try-catch blocks when decoding URLs from external sources.

What's the difference between %20 and + for spaces?

%20 is the standard URL encoding for spaces. The + symbol is specific to application/x-www-form-urlencoded data (HTML forms) and should not be used in URLs directly.

How do I handle international characters in URLs?

International characters are converted to UTF-8 bytes then percent-encoded. "测试" becomes "%E6%B5%8B%E8%AF%95". Always use UTF-8 encoding for consistent results.

How do I detect if a string is already URL-encoded?

Check for % characters followed by valid hex digits. A simple test: if the string contains % and decoding it produces different output, it was likely already encoded.

What happens if I encode a URL twice?

Double encoding creates invalid URLs. For example, a space becomes %20, then %2520. The server receives %2520 instead of the original space, causing incorrect data processing.

Are there size limits for URL encoding?

Most browsers limit URLs to 2048 characters total. Encoded characters take 3x space (%20 vs space), so heavily encoded URLs can hit limits quickly. Use POST requests for large data.

How do I handle URL encoding in different programming languages?

JavaScript: encodeURIComponent(). Python: urllib.parse.quote(). Java: URLEncoder.encode(). PHP: urlencode(). Each language may have slight differences in handling edge cases.