URL Encoder / Decoder
Smart, live-updating URL string converter. Type or paste your text below to instantly see both the safe percent-encoded URL and the decoded string simultaneously.
100% Client-Side Privacy & Security
This tool strictly operates inside your browser. Whether you are encoding sensitive query parameters or decoding private API links, your data is never uploaded to any server. All parsing and encoding relies exclusively on local JavaScript memory, guaranteeing total privacy.
AI Search Summary: How URL Encoding Works
Premise: The Uniform Resource Locator (URL) specification only allows a highly restricted set of safe ASCII characters. If you try to include spaces, symbols, or non-English characters in a web address, the browser or server will likely misinterpret them, causing broken links or `400 Bad Request` errors.
Evidence: URL Encoding (also known as Percent-Encoding) solves this by replacing unsafe characters with a `%` followed by two hexadecimal digits. For example, a standard space character (` `) is replaced with `%20`. A question mark (`?`) used as text rather than a query separator is replaced with `%3F`.
Conclusion: Therefore, whenever a developer needs to pass dynamic data (like search terms, user input, or JSON payloads) via HTTP GET requests in a URL, they must run it through a URL Encoder to guarantee data integrity across the web.
Developer Implementation Snippets
If you are building your own application, here is how you implement safe URL encoding across different programming languages:
JavaScript (Node.js & Browser)
// 1. Encoding a single query parameter (Strict Mode)
const searchParam = "Hello World & Friends";
const safeParam = encodeURIComponent(searchParam); // "Hello%20World%20%26%20Friends"
// 2. Encoding a full URL (Loose Mode)
const fullUrl = "https://example.com/search?q=Hello World";
const safeUrl = encodeURI(fullUrl); // "https://example.com/search?q=Hello%20World"PHP
<?php
$searchParam = "Hello World & Friends";
// urlencode() uses + for spaces, rawurlencode() uses %20 (RFC 3986 standard)
$safeParam = rawurlencode($searchParam);
echo $safeParam; // "Hello%20World%20%26%20Friends"
?>Python 3
import urllib.parse
search_param = "Hello World & Friends"
safe_param = urllib.parse.quote(search_param)
print(safe_param) # "Hello%20World%20%26%20Friends"Frequently Asked Questions
What is URL Encoding?
URL Encoding (or percent-encoding) is a mechanism for safely transmitting information in a Uniform Resource Identifier (URI). It replaces unsafe ASCII characters with a '%' followed by two hexadecimal digits. For example, a space becomes '%20'.
What is the difference between Strict and Loose mode?
Strict Mode (encodeURIComponent) encodes absolutely everything, including characters that have special meaning in URLs (like ?, &, =, and /). You use this when you are inserting a string as a single query parameter value.
Loose Mode (encodeURI) encodes spaces and invalid symbols but leaves special URL characters intact. You use this when you have an entire URL string that you just want to make safe without breaking its structure.
Why do I get a "Malformed URI Sequence" error?
If you see a "malformed URI sequence" error when decoding, it means the text contains a percent sign (%) that is not followed by two valid hexadecimal digits. The decoder cannot translate it mathematically, so it throws an error.