What is URL encoding (percent encoding)?

URL encoding converts characters that are not allowed or have special meaning in a URL into a percent-sign followed by two hexadecimal digits. For example, a space becomes %20 and a Korean character like 안 becomes %EC%95%88.

Why do spaces become %20 in URLs?

Spaces are not valid in a URL. RFC 3986 requires non-unreserved characters to be percent-encoded. A space is represented as %20 (hexadecimal 20 = decimal 32 = ASCII space). Some systems use + instead of %20 in query strings, but %20 is more universally correct.

What is the difference between encodeURIComponent and encodeURI?

encodeURIComponent encodes everything except letters, digits, and - _ . ! ~ * ' ( ). It is designed for encoding individual query parameter values. encodeURI preserves characters that are valid in a complete URL such as :, /, ?, &, =, #, and @, so it is suited for encoding a full URL.

Which characters do not need to be URL-encoded?

The unreserved characters defined in RFC 3986 never need encoding: A–Z, a–z, 0–9, hyphen (-), underscore (_), period (.), and tilde (~). All other characters should be percent-encoded when they appear as data.

What is double-encoding and how do I avoid it?

Double-encoding happens when an already-encoded string is encoded again, turning %20 into %2520. Always decode first if the input may already be encoded, or check whether the value contains existing % sequences before encoding.

How are Korean and CJK characters encoded in URLs?

Korean and CJK characters are first converted to their UTF-8 byte sequences, then each byte is percent-encoded. For example, the Korean word 안녕 is encoded as %EC%95%88%EB%85%95 because its UTF-8 bytes are EC 95 88 EB 85 95.

How does URL encoding work in HTML form submission?

When an HTML form uses method=GET, the browser serializes the form data using application/x-www-form-urlencoded format, which encodes spaces as + and other special characters as percent sequences. When using method=POST with multipart/form-data, no URL encoding is applied.

How should I encode URL parameters in a REST API?

Use encodeURIComponent for each query parameter name and value individually before concatenating them into the URL. Never pass an unencoded user-supplied string directly into a URL, as it can break the URL structure or create security issues.

URL 인코더

텍스트·URL을 퍼센트 인코딩으로 변환

encodeURIComponent — ?, &, =, #, / 포함 대부분의 특수문자를 인코딩

입력

0 chars

인코딩 결과 복사