What is URL encoding?

URL encoding (percent-encoding) replaces unsafe characters with a % followed by two hex digits. For example, a space becomes %20 and an ampersand becomes %26. This ensures special characters don't break URL parsing.

Which characters need to be URL-encoded?

Characters that have special meaning in URLs must be encoded: spaces, &, =, ?, #, /, @, and non-ASCII characters. Letters, digits, and - _ . ~ are safe and don't need encoding.

How do I encode a URL parameter?

Paste the parameter value (not the entire URL) and click Encode. For example, if your search query is 'hello world & more', encoding produces 'hello%20world%20%26%20more', which is safe to use in a URL query string.

What's the difference between encodeURI and encodeURIComponent?

encodeURI encodes a full URL but preserves URL-structural characters like :, /, ?, #, &. encodeURIComponent encodes everything except letters, digits, and - _ . ~ — use it for individual parameter values.

URL エンコード/デコード

URL コンポーネントを安全に変換

Input

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Output

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Encode URL components without breaking your queries

Special characters — spaces, ampersands, slashes, non-ASCII letters — break query strings if they're not percent-encoded. The right tool for the job depends on whether you're encoding a full URL or a single component, and choosing wrong is a frequent source of bugs. This tool handles both cases and shows you exactly what each character becomes.

Use the tool when you need to

Encode a query parameter value

Percent-encode a search term, slug, or special string before slotting it into a query string.

Decode a URL from a log

Reverse %20, %2F, and other escapes to read what the request actually contained.

Audit an OAuth or callback URL

Check that the redirect, scope, and state parameters are encoded correctly before debugging the flow.

How to encode or decode URL components

1
Paste the URL or component into the input area.
2
Click Encode or Decode based on which direction you need.
3
Copy the result and slot it back into your URL or test request.

Keep going

Encode binary as Base64

Pick Base64 when the goal is binary safety rather than URL safety.

Format JSON URLs

Pretty-print payloads that contain encoded URLs as values.

Decode JWTs

Decode auth tokens that may travel through URL parameters.

Validate JSON

Validate JSON bodies that include URL fields.

Common URL-encoding workflows

Build a search redirect

Encode the user's query before constructing the destination URL to avoid breaking on spaces or symbols.

Read a redirect from logs

Decode a logged URL to confirm what the user clicked and which parameters arrived.

Verify an OAuth state parameter

Decode the state to confirm it round-trips through the auth provider untouched.

よくある質問

URLエンコード（percent-encoding）は、URL内で安全でない文字を「%」+16進2桁に置き換える方式です。たとえばスペースは%20、アンパサンドは%26になります。これにより、特殊文字がURLの解析を壊すのを防げます。

URL内で特別な意味を持つ文字はエンコードが必要です。例として、スペース、&, =, ?, #, /, @、および非ASCII文字などがあります。一方、英数字と - _ . ~ は安全な文字で、通常はエンコード不要です。

パラメータ値（URL全体ではなく値の部分）を貼り付けて「Encode」をクリックします。たとえば検索クエリが 'hello world & more' の場合、エンコード結果は 'hello%20world%20%26%20more' となり、クエリ文字列に安全に入れられます。

encodeURIはURL全体向けで、:, /, ?, #, & のようなURL構造に関わる文字は保持します。encodeURIComponentは英数字と - _ . ~ 以外を基本的にすべてエンコードするため、個々のパラメータ値にはこちらを使うのが適切です。