JWT Decoder

Decode JSON Web Tokens and inspect claims

🔒 100% ブラウザ内🆓 ずっと無料⚡ サインアップ不要
注意: 下記のツールインターフェースは現時点で英語のみに対応しています。UI の翻訳は順次進めています。 このツールを英語で見る →

使い方

  1. 1
    Paste your JWT

    Drop the token (header.payload.signature) into the input box.

  2. 2
    Inspect the header and payload

    The three base64url segments are decoded and formatted as JSON.

  3. 3
    Check the claims

    Standard claims like exp, iat, nbf are shown with human-readable dates and an expired/valid badge.

JWT Decoder について

Free online JWT decoder. Paste any JSON Web Token to decode the header, payload, and signature. See standard claims (iss, sub, exp, iat) formatted with human-readable timestamps and an expiry indicator. All decoding happens in your browser. 712 Tools の JWT Decoder はモダンな JavaScript API を使って完全にブラウザ内で動作します - サーバーがあなたのデータを見ることは一切ありません。つまり、即時の結果、完全なプライバシー、アップロード制限なしです。

デバッグ、簡単な確認、あるいは本番のインシデント対応まで - このツールは何度でも無料で使えます。ウォーターマークなし、サインアップなし、ツール内広告なし。

よくある質問

Does it verify the signature?

No. This tool only decodes the token - verifying signatures requires the secret or public key, which should never be pasted into a public web tool.

Is my token uploaded?

Never. All base64url decoding happens locally in your browser. Nothing is stored, logged, or sent.

Is it safe to paste production tokens?

Because decoding happens locally, yes - no network request is made. Still, treat any browser tool with care and prefer a local CLI for the most sensitive tokens.

What algorithms are supported?

The header shows any 'alg' value. Decoding is algorithm-independent since it only parses the base64url segments.

続きを読む

5 分で読了

From curl to fetch, axios, and Python: the API integration workflow

Every API doc uses curl examples. Every codebase uses something else. Here's how to translate curl commands correctly - headers, auth, JSON bodies, and the flags that don't map cleanly.

6 分で読了

JWT explained: what actually goes inside that token

Every login flow you touch these days involves JWTs, but 'JSON Web Token' hides a lot. Here's the three-part structure, the security pitfalls, and when not to use them.

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