Should spaces be + or %20?

In query strings (application/x-www-form-urlencoded), spaces can be + or %20. In URL paths, use %20. encodeURIComponent always produces %20; form data typically uses +. Both decode to space correctly.

Why do some characters encode to multiple %XX?

URL encoding works on bytes, not characters. UTF-8 encodes non-ASCII characters as multiple bytes. The Euro sign (€) is 3 UTF-8 bytes (E2 82 AC), so it becomes %E2%82%AC. This is correct behavior.

Do I need to encode the entire URL?

No! Only encode the parts that contain user data or special characters. Never double-encode an already-encoded URL. Parse the URL, encode just the parameter values, then reconstruct.

How do I encode a URL that's already partially encoded?

Be careful of double encoding (%20 becoming %2520). Decode first if unsure: decodeURIComponent(str).then(encodeURIComponent). Or parse with URL constructor to let the browser handle it.

URL Encoder

Guide & TutorialOffline

Encode text for use in URLs (percent encoding)

Encode text for URLs instantly with our free online URL encoder tool. This encoder helps web developers and API users convert special characters into percent-encoded format for safe transmission in URLs and query strings. Simply paste your text and get the URL-encoded output in real-time.

Input Text

0 characters

URL Encoded Output

About URL Encoding

URL encoding converts characters into a format that can be transmitted over the Internet. Special characters are replaced with a percent sign (%) followed by two hexadecimal digits.

About URL Encoder

URL encoding (percent encoding) converts special characters into a format safe for URLs. Characters like spaces, &, =, and non-ASCII characters are replaced with % followed by their hexadecimal byte values. This is essential for query parameters, form submissions, and any data passed via URLs.

How It Works

The encoder identifies characters that aren't URL-safe (letters, digits, -_.~) and converts each byte to %XX format where XX is the hexadecimal value. Spaces can become %20 or + depending on context. UTF-8 strings may produce multiple %XX sequences per character (e.g., € becomes %E2%82%AC).

Technical Details

RFC 3986 defines unreserved characters (A-Z, a-z, 0-9, -_.~) that don't need encoding. Reserved characters (:/?#[]@!$&'()*+,;=) have special URL meanings and must be encoded when used as data. The application/x-www-form-urlencoded format (HTML forms) additionally encodes spaces as + and handles special cases for form data.

Common Use Cases

Query String Parameters

Encode values in URL query strings to handle special characters.

?search=hello world becomes ?search=hello%20world

Form Data Submission

Browser forms encode data before sending as POST body or GET query.

API Requests

Encode user input before including in API URLs.

File Names in URLs

Safely include file names with spaces or special characters in download links.

OAuth & Authentication

Properly encode redirect URIs and callback URLs.

Code Examples

JavaScript

javascript

// Encode query parameter value
const encoded = encodeURIComponent('hello world & goodbye');
// Result: "hello%20world%20%26%20goodbye"

// Build URL with parameters
const params = new URLSearchParams({
  name: 'John Doe',
  city: 'New York'
});
const url = 'https://api.example.com/search?' + params.toString();
// Automatically encodes: ?name=John+Doe&city=New+York

// Don't double encode!
const alreadyEncoded = 'hello%20world';
// WRONG: encodeURIComponent(alreadyEncoded) = "hello%2520world"

Use URLSearchParams for building query strings - it handles encoding automatically.

Python

python

from urllib.parse import urlencode, quote, quote_plus

# Encode single value
encoded = quote('hello world')  # hello%20world
encoded = quote_plus('hello world')  # hello+world (form style)

# Build query string
params = urlencode({'name': 'John Doe', 'city': 'São Paulo'})
# name=John+Doe&city=S%C3%A3o+Paulo

# Encode path component
path = quote('my file.pdf', safe='')
# my%20file.pdf

quote() uses %20 for spaces, quote_plus() uses + (form encoding). urlencode() handles entire dictionaries.

Tips & Best Practices

Use URLSearchParams/urlencode for query strings instead of manual encoding
Always encode user input before putting it in URLs
Be aware of double-encoding when working with already-encoded strings
Test with Unicode characters like emoji and international text
Remember that + and %20 both represent space in query strings

Common Mistakes to Avoid

Double encoding (encoding already-encoded strings)
Using encodeURI for parameter values (use encodeURIComponent)
Not encoding user input, allowing URL injection
Forgetting that encodeURIComponent doesn't encode -_.~!*()'

When to Use This Tool

Use URL encoding whenever inserting variable data into URLs: query parameters, path segments, form submissions. Essential for preventing URL injection and handling special characters in web applications.

Frequently Asked Questions

encodeURI encodes a complete URL, preserving :/?#[]@!$&'()*+,;= which have URL meanings. encodeURIComponent encodes everything except letters/digits/-_.~, making it suitable for query parameter values. Use encodeURIComponent for user input in parameters.

// Encode query parameter value const encoded = encodeURIComponent('hello world & goodbye'); // Result: "hello%20world%20%26%20goodbye" // Build URL with parameters const params = new URLSearchParams({ name: 'John Doe', city: 'New York' }); const url = 'https://api.example.com/search?' + params.toString(); // Automatically encodes: ?name=John+Doe&city=New+York // Don't double encode! const alreadyEncoded = 'hello%20world'; // WRONG: encodeURIComponent(alreadyEncoded) = "hello%2520world"

from urllib.parse import urlencode, quote, quote_plus # Encode single value encoded = quote('hello world') # hello%20world encoded = quote_plus('hello world') # hello+world (form style) # Build query string params = urlencode({'name': 'John Doe', 'city': 'São Paulo'}) # name=John+Doe&city=S%C3%A3o+Paulo # Encode path component path = quote('my file.pdf', safe='') # my%20file.pdf