URL Encoding Complete Guide: Why %20 Exists and How to Handle It

Every web developer encounters URL encoding. But why does a space become %20? Here is the complete guide. What Is URL Encoding? URLs can only use a limited set of ASCII characters. URL encoding converts unsafe characters to %XX format. Space -> %20 / -> %2F ? -> %3F & -> %26 = -> %3D JavaScript // For values in query params encodeURIComponent ( ' hello world & goodbye ' ) // 'hello%20world%20%26%20goodbye' // For full URLs (preserves :, /, ?, &) encodeURI ( ' https://example.com/path?q=hello world ' ) Rule : Use encodeURIComponent for values, encodeURI for full URLs. Python from urllib.parse import quote , quote_plus quote ( ' hello world ' ) # 'hello%20world' quote_plus ( ' hello world ' ) # 'hello+world' The Double Encoding Trap Original: hello world Encoded once: hello%20world Encoded twice: hello%2520world <- BUG! If you see %25 in URLs, you are double-encoding. Try It Online Encode and decode URLs with DevToolBox URL Encoder - handles all special characters. Have you been burned b