URL Encoding & Decoding Code Examples

// Encode a query parameter value
const param = encodeURIComponent('hello world & more');
console.log(param); // "hello%20world%20%26%20more"

// Encode a full URL (preserves :, /, ?, #, etc.)
const url = encodeURI('https://example.com/path?q=hello world');
console.log(url); // "https://example.com/path?q=hello%20world"

// Build a query string safely
const params = new URLSearchParams({
  query: 'hello world',
  page: '1',
  filter: 'name=test&value=42'
});
console.log(params.toString());

// Decode a component
const decoded = decodeURIComponent('hello%20world%20%26%20more');
console.log(decoded); // "hello world & more"

// Decode a full URL
const url = decodeURI('https://example.com/path?q=hello%20world');
console.log(url);

// Parse query string parameters
const params = new URLSearchParams('?query=hello+world&page=1');
console.log(params.get('query')); // "hello world"

from urllib.parse import quote, urlencode

# Encode a single string
encoded = quote('hello world & more')
print(encoded)  # "hello%20world%20%26%20more"

# Encode query parameters
params = urlencode({
    'query': 'hello world',
    'page': 1,
    'filter': 'name=test&value=42'
})
print(params)

# quote_plus uses + for spaces (form encoding)
from urllib.parse import quote_plus
print(quote_plus('hello world'))  # "hello+world"

from urllib.parse import unquote, parse_qs, urlparse

# Decode a string
decoded = unquote('hello%20world%20%26%20more')
print(decoded)  # "hello world & more"

# Parse a full URL with query params
url = 'https://example.com/search?q=hello%20world&page=2'
parsed = urlparse(url)
params = parse_qs(parsed.query)
print(params)  # {'q': ['hello world'], 'page': ['2']}

<?php
// urlencode: spaces become +
echo urlencode('hello world & more');
// "hello+world+%26+more"

// rawurlencode: spaces become %20 (RFC 3986)
echo rawurlencode('hello world & more');
// "hello%20world%20%26%20more"

// Build a query string
$params = http_build_query([
    'query' => 'hello world',
    'page' => 1,
]);
echo $params; // "query=hello+world&page=1"

<?php
echo urldecode('hello+world+%26+more');
// "hello world & more"

echo rawurldecode('hello%20world%20%26%20more');
// "hello world & more"

// Parse a query string into an array
parse_str('query=hello+world&page=1', $params);
print_r($params);
// Array ( [query] => hello world [page] => 1 )

package main

import (
    "fmt"
    "net/url"
)

func main() {
    // Encode a single value
    encoded := url.QueryEscape("hello world & more")
    fmt.Println(encoded) // "hello+world+%26+more"

    // Path encoding (spaces -> %20)
    pathEncoded := url.PathEscape("hello world & more")
    fmt.Println(pathEncoded)

    // Build query params safely
    params := url.Values{}
    params.Set("query", "hello world")
    params.Set("page", "1")
    fmt.Println(params.Encode())
}

package main

import (
    "fmt"
    "net/url"
)

func main() {
    decoded, err := url.QueryUnescape("hello+world+%26+more")
    if err != nil {
        panic(err)
    }
    fmt.Println(decoded) // "hello world & more"

    // Parse a full URL
    u, _ := url.Parse("https://example.com/search?q=hello+world&page=2")
    fmt.Println(u.Query().Get("q")) // "hello world"
}

import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;

// Encode a query parameter
String encoded = URLEncoder.encode(
    "hello world & more", StandardCharsets.UTF_8
);
System.out.println(encoded); // "hello+world+%26+more"

// For path segments, replace + with %20
String pathEncoded = encoded.replace("+", "%20");
System.out.println(pathEncoded);

import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;

String decoded = URLDecoder.decode(
    "hello+world+%26+more", StandardCharsets.UTF_8
);
System.out.println(decoded); // "hello world & more"

// Cargo.toml: urlencoding = "2"
use urlencoding::{encode, decode};

fn main() {
    // Encode
    let encoded = encode("hello world & more");
    println!("{}", encoded); // "hello%20world%20%26%20more"

    // Decode
    let decoded = decode("hello%20world%20%26%20more").unwrap();
    println!("{}", decoded); // "hello world & more"
}

using System;
using System.Web;

// RFC 3986 compliant (recommended)
string encoded = Uri.EscapeDataString("hello world & more");
Console.WriteLine(encoded); // "hello%20world%20%26%20more"

// Form encoding (+ for spaces)
string formEncoded = HttpUtility.UrlEncode("hello world & more");
Console.WriteLine(formEncoded); // "hello+world+%26+more"

// Decode
string decoded = Uri.UnescapeDataString("hello%20world");
Console.WriteLine(decoded); // "hello world"

require 'cgi'
require 'uri'

# Form encoding (spaces -> +)
puts CGI.escape('hello world & more')
# "hello+world+%26+more"

# Decode
puts CGI.unescape('hello+world+%26+more')
# "hello world & more"

# Build query string
puts URI.encode_www_form(query: 'hello world', page: 1)
# "query=hello+world&page=1"

# Using curl's --data-urlencode
curl -G --data-urlencode "q=hello world & more" https://example.com/search

# Using Python one-liner
echo "hello world & more" | python3 -c \
  "import sys, urllib.parse; print(urllib.parse.quote(sys.stdin.read().strip()))"
# Output: hello%20world%20%26%20more

Character  Encoded    Notes
---------  -------    -----
(space)    %20        or + in form data
!          %21
#          %23        Fragment identifier
$          %24
%          %25        Escape character itself
&          %26        Parameter separator
+          %2B        Space in form encoding
/          %2F        Path separator
=          %3D        Key-value separator
?          %3F        Query string start
@          %40