URL Encoder/Decoder Guide
URL Encoding, also known as Percent Encoding, is a method to convert characters into a format that can be transmitted over the Internet. URLs can only be sent over the Internet using the ASCII character-set, so URL Encoding replaces unsafe ASCII characters with a '%' followed by two hexadecimal digits.
You should use URL encoding when:
- Including special characters in URLs
- Sending form data (application/x-www-form-urlencoded)
- Embedding user input in query strings
- Including non-ASCII characters in URLs
- Storing data in cookies or local storage
The terms 'URL Encoding' and 'URI Encoding' are often used interchangeably, but there are technical differences. URIs (Uniform Resource Identifiers) are a superset of URLs.
In JavaScript, encodeURI() preserves characters that are part of URI syntax (like ':', '/', '?'), while encodeURIComponent() encodes more characters, making it safer for query parameters.
Common character encodings include:
- Space: %20 (or + in query strings)
- !: %21
- ": %22
- #: %23
- $: %24
- %: %25
- &: %26
- ': %27
- (: %28
- ): %29
- *: %2A
- +: %2B
- ,: %2C
- /: %2F
- :: %3A
- ;: %3B
- =: %3D
- ?: %3F
- @: %40
- [: %5B
- ]: %5D
Spaces in URLs can be encoded in two ways:
- As '%20' (the percent encoding for the space character)
- As '+' (in application/x-www-form-urlencoded format, commonly used in query strings)
Be aware of which format you need to use depending on where in the URL you're encoding characters.
Most programming languages provide built-in functions for URL encoding:
- JavaScript:
encodeURIComponent(),encodeURI() - PHP:
urlencode(),rawurlencode() - Python:
urllib.parse.quote(),urllib.parse.quote_plus() - Java:
URLEncoder.encode() - Ruby:
URI.encode_www_form_component() - C#:
HttpUtility.UrlEncode()
Proper URL encoding is crucial for security:
- It prevents injection attacks when user input is included in URLs
- It helps avoid broken links due to special characters
- It prevents data corruption when transmitting non-ASCII characters
Always encode user-provided data before including it in URLs, especially in query parameters.
What is the difference between URL encoding and URI encoding?
URL encoding is specifically for Uniform Resource Locators while URI encoding applies to Uniform Resource Identifiers (a superset of URLs). In practice, JavaScript provides encodeURI() which preserves URI syntax characters like ':/?#' and encodeURIComponent() which encodes all special characters, making it safer for encoding individual URL components.
Do I need to encode entire URLs?
No, you should only encode specific parts of URLs, typically the query parameters or path segments containing special characters. Encoding an entire URL would break its structure by encoding the protocol, slashes, and other syntax characters.
How are spaces handled in URL encoding?
Spaces can be encoded in two ways: as '%20' (standard percent encoding) or as '+' (used in application/x-www-form-urlencoded format, common in query strings). Both are valid, but they're used in different contexts.
Why does my browser sometimes show encoded URLs and sometimes not?
Browsers may display decoded URLs in the address bar for readability, but they're still stored and transmitted in encoded form. View the page source or network requests to see the actual encoded values.
Is my data safe when using this URL encoder/decoder?
Yes, all processing happens client-side in your browser. Your data is never sent to our servers, ensuring your privacy.