URLエンコーダー / デコーダー

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ツールについて

URL エンコーダはスペース・&・=・?・/ や非 ASCII など URL 内で安全でない文字を %xx パーセントエンコーディングに変換します。エンコードしないと URL 構造が壊れます。フレームワークは自動でやってくれますが、文字列結合で URL を組み立てる時は手動で必要です。

使い方

  1. Choose Encode to escape characters, or Decode to recover the original.
  2. Paste the URL or query parameter into the input box.
  3. The output updates as you type — no submit button.
  4. Copy the encoded string into your URL builder, fetch call, or query string.
  5. When in doubt, encode each query parameter individually rather than the whole URL.

主な使用例

  • Building a search URL where the query contains spaces or special characters.
  • Generating a redirect URL that passes another URL as a parameter.
  • Constructing a deep link with non-ASCII text (Korean, Japanese, emoji) in the path.
  • Decoding a webhook payload where parameters are URL-encoded twice.
  • Sanity-checking that a third-party callback URL is properly escaped.
  • Encoding a base64 string before placing it in a URL — the + and / are unsafe.

よくある質問

Q. What is the difference between encodeURI and encodeURIComponent?

A. encodeURI keeps reserved URL characters (: / ? & =) intact — use it for whole URLs. encodeURIComponent escapes them too — use it for individual parameter values.

Q. Why is a space sometimes encoded as + and other times as %20?

A. + is the legacy x-www-form-urlencoded form (still used in query strings), %20 is the standard percent-encoding used in URL paths. Servers normally accept either in query strings.

Q. Do I need to encode non-ASCII characters?

A. Yes, for compatibility. Modern browsers display Unicode in the URL bar, but the underlying request encodes them as UTF-8 percent-escapes.

Q. Why does decoding produce strange characters?

A. Usually a charset mismatch — the URL was encoded with one encoding (e.g., latin-1) but decoded as another (UTF-8). Fix the source if you can.