URL Encoder / Decoder

Percent-Encoding Explained: Why URLs Look Like %EC%95%88

Every URL travels through systems that only understand a narrow set of ASCII characters. Percent-encoding (RFC 3986) is the bridge: any byte outside the safe set becomes a % followed by its hexadecimal value. Korean text, spaces, and special symbols all pass through the web this way.

1. When You Need This Tool

• Building API requests: query values containing &, =, or spaces must be encoded or the server misparses them.
• Reading logs and analytics: decoding reveals what users actually searched for.
• Sharing Korean URLs: messengers often show the encoded form — decoding restores the readable address.

2. Component vs Full URL

encodeURIComponent escapes everything — perfect for a single parameter value. encodeURI preserves :, /, ?, # so a whole address keeps its structure. Using the wrong one is a classic bug: double-encoded parameters or broken paths.

3. Common Pitfalls

Double encoding (%2520 instead of %20) happens when an already-encoded string is encoded again. Decode errors usually mean a stray % not followed by two hex digits. When in doubt, decode repeatedly until the text stops changing.