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URL Encoder / Decoder

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About URL Encoder / Decoder

URL Encoding and Decoding for Improved Web Performance


URL encoding and decoding may seem like an obscure technical topic, but these techniques are critical for proper functioning and optimization of websites and web applications. By converting special characters into a standardized format, URL encoding facilitates accurate transmission of text in URLs and form data. Read on to learn what URL encoding and decoding involve, why they matter for performance, and how to use them effectively.


What is URL Encoding?

URL encoding converts characters into a format that can be properly interpreted when transmitted over the internet. It substitutes special characters with a percent sign (%) followed by hexadecimal digits that represent those characters' byte sequence in ASCII or UTF-8.

For example, spaces are converted to %20. This prevents spaces and other special characters from being misinterpreted as delimiters when included in URLs and query strings. URL encoding adheres to specifications in RFC 1738 for allowable URL characters.




When is URL Encoding Used?

URL encoding has several common uses:

  • Encoding components of website URLs - Special characters need to be converted to avoid errors.
  • Form data submission - User inputs containing spaces, symbols, accents etc. must be encoded.
  • Protecting sensitive information - Encoding can mask info like usernames and passwords.
  • JavaScript redirection - Encoding allows special chars to be included.
  • Building valid query strings - Encoding parameters ensures proper API function.

URL encoding is applied automatically in many cases, but developers may also manually encode data.


What is the Use of URL Encoding?

According to the URL specification RFC 1738, only a limited amount of characters may be used in a URL. These characters are as follows:


a to z (abcdefghijklmnopqrstuvwxyz) _ (Underscore)
0 to 9 (0123456789) . (Period)
$ (Dollar Sign) ! (Exclamation or Bang)
+ (Plus sign) * (Asterisk or Star)
( (Open Bracket) ‘ (Single Quote)
) (Closing Bracket)  










How does URL Encoding work?

Online URL encoding, also known as Percent-encoding, is a method of encoding specific information in a Uniform Resource Identifier (URI) in specified circumstances. Despite the fact that it is commonly referred to as URL encoding, it is generally utilized within the main Uniform Resource Identifier (URI) set, which includes both Uniform Resource Locator (URL) and Uniform Resource Name (URN).

This online URL encoding is also used in data preparation and HTML form data submission in HTTP queries.

All characters that must be modified are replaced by a percent sign (%) and a two-digit hexadecimal value representing the character in the relevant ISO character set. Some instances are provided below:


$ (Dollar Sign) becomes %24 + (Plus) becomes %2B
& (Ampersand) becomes %26 , (Comma) becomes %2C
: (Colon) becomes %3A ; (Semi-Colon) becomes %3B
= (Equals) becomes %3D ? (Question Mark) becomes %3F
@ (Commercial A / At) becomes %40  




How Does the URL Encoding Process Work?

URL encoding works by:

  1. Identifying non-ASCII and reserved characters to be encoded.
  2. Converting each character to its byte sequence in UTF-8.
  3. Representing each byte as a two-digit hexadecimal value preceded by %%.

For example, a space character is converted to the 3-byte UTF-8 sequence 11000011 10100000 10000000. Each byte is then rendered as its hex equivalent - %20. The full space character is replaced with %20.

This hex encoding scheme ensures that all special characters can be reliably transmitted over the internet. Plus, the encoded URLs remain reasonably compact and readable.


What is URL Decoding?

URL decoding performs the reverse process of converting encoded characters back into the original characters. It translates hexadecimal values preceded by % into their corresponding symbols and accented characters.

URL decoding allows developers to restore encoded information back into a readable format. It is used to display human-readable URLs, reveal encrypted data, and process form data.




How are Encoded URLs Decoded?

URL decoders work by:

  1. Identifying %xx sequences in an encoded URL or query string.
  2. Converting each %xx hex set into its decimal value.
  3. Mapping the decimal values back to their character equivalents in UTF-8 or ASCII.
  4. Replacing all %xx instances with the matching symbols, accents, and spaces.

This decoding restores the original special characters so that encoded data can be processed and displayed correctly.


Why Does URL Encoding and Decoding Matter?

URL encoding and decoding may seem esoteric, but they are critical for security and performance. Key benefits include:

  • Avoiding errors caused by spaces and symbols in URLs - Encoding standardizes URLs for reliable transmission.
  • Allowing special characters in form data - User inputs with spaces, accents and symbols can be submitted.
  • Masking sensitive parameters like API keys - Encoding obscures information from being viewed.
  • Compressing UTF-8 multi-byte sequences - More compact encoded URLs require less bandwidth.
  • Facilitating international URLs - Encoding handles accented and non-Latin characters.
  • Providing consistent parsing of parameters - Decoding ensures API reliability.

Following encoding best practices enhances website functionality while decoding reveals encoded information for processing.




Best Practices for URL Encoding

Here are some tips for effectively implementing URL encoding:

  • Selectively target special characters - Only encode the minimum necessary characters rather than entire URLs.
  • Encode appropriate inputs - User entered form data often requires encoding.
  • Use encoding for security - Mask API keys, usernames and passwords via encoding.
  • Specify encoding for APIs - Many platforms require encoded parameters.
  • Decode data prior to processing - Encode for transmission, then decode for usage.
  • Avoid double encoding - Multiple encodings can break functionality.
  • Encode unfamiliar text - Non-Latin and accented characters commonly need encoding.

With a bit of care, URL encoding and decoding allows developers to include special characters while optimizing web performance. By converting to standardized hexadecimal representations, URLs and queries remain efficient and stable as they pass through servers. Simply remember to decode encoded text back into human-readable form before usage in your applications.