URL encoding converts characters into a format that can be safely transmitted over the internet. Since URLs can only be sent over the Internet using the ASCII character set, characters that are not in this set or have special meanings (like spaces, &, =) must be encoded. encodeURIComponent escapes all characters except A-Z a-z 0-9 - _ . ! ~ * ' ( ).

encodeURI() is intended to encode a complete URL, preserving characters that have syntactic meaning in a URL (like ://, ?, #). encodeURIComponent() is meant to encode a single component (like a query parameter value) and will encode all characters that are not unreserved, including / ? & = #. Use encodeURIComponent when you need to safely embed a value into a query string or path segment.

It encodes all characters except the following unreserved set: A-Z a-z 0-9 - _ . ! ~ * ' ( ). Even characters like @, #, $, &, +, =, /, and ? are converted to percent-encoded sequences.

Use decodeURIComponent(). However, invalid sequences (like %ZZ) will throw a URIError. Always wrap the call in a try...catch block to handle malformed input gracefully. Our tool does this automatically and shows a clear error message.

It is essential when building query strings dynamically, embedding user input into URLs, constructing REST API calls, or passing data via the browser’s window.open or fetch with parameters. Without proper encoding, special characters could break the URL structure or introduce security vulnerabilities like injection attacks.