URL Encoder / Decoder: Encode Decode URLs Online Free

URL encoding (also called percent-encoding) is essential for transmitting data over the web safely. Every time you submit a form, paste a URL with special characters, or send data via query parameters — URL encoding is working behind the scenes.

Understanding URL Encoding

The HTTP protocol only allows a limited set of characters in URLs: letters, digits, hyphens, underscores, tildes, and periods. All other characters must be encoded using percent-encoding, which converts each byte to a %XX format where XX is the hexadecimal ASCII code of the character.

When Do You Need URL Encoding?

• Query parameters — spaces and special chars in search queries (?q=hello world → ?q=hello%20world)
• Path parameters — file names with spaces or non-ASCII characters
• Form submissions — application/x-www-form-urlencoded format
• API requests — embedding JSON or special characters in query strings
• Bookmarklets — JavaScript URLs with encoded parameters

Key Characters Reference

URL Encoding in Different Languages

JavaScript

// Encode
encodeURIComponent("hello world");  // "hello%20world"
encodeURI("https://example.com/a b");  // "https://example.com/a%20b"

// Decode
decodeURIComponent("hello%20world");  // "hello world"

Python

from urllib.parse import quote, urlencode, unquote

# Encode
quote("hello world")          # "hello%20world"
quote("hello world", safe="")  # force encode spaces

# Query dict
urlencode({{"name": "Alice", "city": "New York"}})
# "name=Alice&city=New%20York"

# Decode
unquote("hello%20world")      # "hello world"

URL Safe Encoding

// encodeURI does NOT encode: A-Za-z0-9-_.~
// Use encodeURIComponent for individual values (aggressive)
// Use encodeURI for full URLs (preserves structural chars)

Common Mistakes to Avoid

• Don't double-encode — encode before sending, decode on receipt. Encoding twice produces %2520 instead of %20
• Don't encode full URLs with encodeURIComponent
• — use encodeURI instead, which preserves :/?#[]@!$&'()*+,;=
• Encode path segments separately — each path segment should be encoded independently
• Handle Unicode properly — always UTF-8 encode before percent-encoding