🔑 JWT Decoder
Decode JSON Web Tokens — see header, payload, and expiration
🔒 画像がデバイスの外に出ることはありません。 すべての処理はJavaScript Base64 decodingを使用してブラウザ内でローカルに行われます。アップロード、サーバー、追跡は一切ありません。
特長
- Full Token Inspection — Decode and display the header, payload, and signature of any JWT token.
- Expiration Check — See issued-at and expiration timestamps with human-readable dates and expiry status.
- Claims Display — View all standard claims — issuer, subject, audience, and custom fields.
- Fully Offline — Decoding happens in your browser. Your tokens are never sent to any server.
仕組み
- Paste your JWT — Paste a JSON Web Token in the input field.
- Inspect the decoded parts — View the header (algorithm, type), payload (claims, timestamps), and signature.
- Check expiration — See whether the token is still valid or has expired.
活用例
- Debug authentication issues by inspecting JWT claims
- Verify token expiration and issuer before trusting it
- Inspect tokens during API development and testing
- Learn about JWT structure by examining real tokens
よくある質問
Does this verify the JWT signature?
This tool decodes the token to show its contents. Signature verification requires the secret key or public key, which we don't collect for privacy reasons.
Is it safe to paste my JWT here?
Yes. Everything runs locally in your browser. Your token is never sent to any server or stored anywhere.
What JWT formats are supported?
Standard three-part JWTs (header.payload.signature) using Base64URL encoding. This covers JWTs from all major identity providers.
関連ツール
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