JWT

Decode a JWT (no signature check)

POSThttps://ecdsa.com/api/v1/jwt/decode

Decodes a compact JWS token: header, payload, enriched exp/iat/nbf time claims and a classification of the algorithm. The signature is NOT verified — the response carries verified: false explicitly. Use /v1/jwt/verify to check ES* signatures.

API キー: 任意（キーには api スコープが必要）
キー使用時のクォータ消費: 呼び出しごとに 1 ユニット
レート制限: IP あたり毎分 60 リクエスト

リクエスト

JSON ボディ：JwtDecodeRequest

フィールド	型	必須	説明
token	string	はい	Compact JWS token. A leading "Bearer " and whitespace are stripped.

レスポンス

200The decoded token (signature not verified).

フィールド	型	必須	説明
header	object	はい	メンバー名は任意
payload	object	はい	メンバー名は任意
signaturePresent	boolean	はい
signatureBytes	integer	はい	0 以上
timeClaims	object	はい
timeClaims.exp	TimeClaim	はい
timeClaims.iat	TimeClaim	はい
timeClaims.nbf	TimeClaim	はい
timeClaims.status	object \| null	はい	null when the token carries no usable exp or nbf.
timeClaims.status.kind	string	はい	"expired"、"not-yet-valid"、または"valid" のいずれか
timeClaims.status.detail	string	はい
algInfo	AlgInfo	はい
verified	boolean	はい	Always false — this operation never verifies. 常に false
note	string	はい

ヘッダー： X-Request-Id · X-RateLimit-Limit · X-RateLimit-Remaining · X-RateLimit-Reset · X-Quota-Limit · X-Quota-Remaining · X-Quota-Reset

ステータス	意味	コード
400	Bad request. Input limits: a request body of at most 100 KB (a larger one is answered with 413) and arrays and objects nested at most 64 levels deep, JSON documents inside string fields included.	invalid_json missing_field invalid_input private_key_rejected
401	Unauthorized.	unauthorized
403	Forbidden.	forbidden_scope
404	Not found.	not_found
405	Method not allowed.	method_not_allowed
413	Payload too large.	payload_too_large
429	Too many requests.	rate_limited quota_exceeded
500	Internal server error.	internal_error
503	Service unavailable.	service_unavailable
504	Gateway timeout.	timeout

エラーのレスポンスにはすべて JSON エンベロープが含まれます。各コードの意味と対処法はエラー一覧表で確認できます。

例

An ES256 token

curl

curl -sS 'https://ecdsa.com/api/v1/jwt/decode' \
  -H 'content-type: application/json' \
  -d '{
  "token": "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImNvcHBlci1leGFtcGxlLTEifQ.eyJpc3MiOiJodHRwczovL2lzc3Vlci5leGFtcGxlLmNvbSIsInN1YiI6InVzZXJfNDIiLCJhdWQiOiJlY2RzYSIsImlhdCI6MTc4NzE0MDgwMCwiZXhwIjo0MDcwOTA4ODAwfQ.fQpTQxkahGRlZp-U71-xNk68mpZH23dhn9QoysMLmZfBx_e-vd9sCgh7sJ4eXu0-WbQSNqzmVPyUKErCJx4DHw"
}'

JavaScript (fetch)

const response = await fetch("https://ecdsa.com/api/v1/jwt/decode", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "token": "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImNvcHBlci1leGFtcGxlLTEifQ.eyJpc3MiOiJodHRwczovL2lzc3Vlci5leGFtcGxlLmNvbSIsInN1YiI6InVzZXJfNDIiLCJhdWQiOiJlY2RzYSIsImlhdCI6MTc4NzE0MDgwMCwiZXhwIjo0MDcwOTA4ODAwfQ.fQpTQxkahGRlZp-U71-xNk68mpZH23dhn9QoysMLmZfBx_e-vd9sCgh7sJ4eXu0-WbQSNqzmVPyUKErCJx4DHw"
  }),
});
console.log(response.status, await response.json());

Python (httpx)

import httpx

response = httpx.post(
    "https://ecdsa.com/api/v1/jwt/decode",
    json={
        "token": "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImNvcHBlci1leGFtcGxlLTEifQ.eyJpc3MiOiJodHRwczovL2lzc3Vlci5leGFtcGxlLmNvbSIsInN1YiI6InVzZXJfNDIiLCJhdWQiOiJlY2RzYSIsImlhdCI6MTc4NzE0MDgwMCwiZXhwIjo0MDcwOTA4ODAwfQ.fQpTQxkahGRlZp-U71-xNk68mpZH23dhn9QoysMLmZfBx_e-vd9sCgh7sJ4eXu0-WbQSNqzmVPyUKErCJx4DHw",
    },
    timeout=30.0,
)
print(response.status_code, response.json())

レスポンス 200

{
  "header": {
    "alg": "ES256",
    "typ": "JWT",
    "kid": "copper-example-1"
  },
  "payload": {
    "iss": "https://issuer.example.com",
    "sub": "user_42",
    "aud": "ecdsa",
    "iat": 1787140800,
    "exp": 4070908800
  },
  "signaturePresent": true,
  "signatureBytes": 64,
  "timeClaims": {
    "exp": {
      "value": 4070908800,
      "utc": "2099-01-01 00:00:00 UTC",
      "relative": "in 72 years"
    },
    "iat": {
      "value": 1787140800,
      "utc": "2026-08-19 12:00:00 UTC",
      "relative": "61 days ago"
    },
    "nbf": null,
    "status": {
      "kind": "valid",
      "detail": "valid until 2099-01-01 00:00:00 UTC (in 72 years)"
    }
  },
  "algInfo": {
    "alg": "ES256",
    "kind": "ecdsa",
    "curve": "P-256",
    "hash": "SHA-256",
    "signatureBytes": 64,
    "verifiableHere": true,
    "summary": "ES256 is ECDSA on P-256 with SHA-256; the JWS signature is raw r‖s (64 bytes). POST /api/v1/jwt/verify can check it."
  },
  "verified": false,
  "note": "This endpoint decodes the token without checking the signature. Use POST /api/v1/jwt/verify (ES256/ES384/ES512) to verify it against a public key."
}

この例に対する API のレスポンスです。2026年10月20日にこのページ用に取得したもので、含まれる相対時間や日数はその日を基準にしています。

エラーコード

コード	ステータス	意味
invalid_json	400	The body is not valid JSON or not a JSON object; or the input nests arrays and objects more than 64 levels deep (JSON documents inside string fields count too), or is too complex to inspect for private keys.
missing_field	400	A required field is absent or empty.
invalid_input	400	A field could not be parsed — the message explains exactly why.
private_key_rejected	400	The request contains private-key material (a PEM PRIVATE KEY block, an OpenSSH, SSH2 or PuTTY private key, or a JWK with "d"). Never send private keys anywhere.
unauthorized	401	The Authorization or X-API-Key header is malformed, the API key is not valid (wrong checksum, unknown, revoked or expired), or the operation needs a key.
forbidden_scope	403	The API key is valid but lacks a scope this operation requires; the message names it.
not_found	404	No operation exists at this path.
method_not_allowed	405	The path exists but does not accept this HTTP method; see the Allow header.
payload_too_large	413	The body exceeds 100 KB.
rate_limited	429	Too many requests — see Retry-After.
quota_exceeded	429	A daily or monthly quota of the API key's account is used up. X-Quota-Reset (and Retry-After) say when it starts over; retrying earlier cannot succeed.
internal_error	500	Unexpected server error.
service_unavailable	503	API keys cannot be verified right now (the key store is unreachable); retry shortly.
timeout	504	The operation did not finish within its time budget.

スキーマ

TimeClaim

null when the claim is absent; {error} when it is malformed.

フィールド	型	必須	説明
構造 1value	number	はい	Seconds since the epoch.
構造 1utc	string	はい
構造 1relative	string	はい	For example "in 72 years" or "3 minutes ago".
構造 2error	string	はい

AlgInfo

Classification of the header's alg value.

フィールド	型	必須	説明
alg	string \| null	はい
kind	string	はい	"ecdsa"、"none"、"hmac"、"rsa"、"eddsa"、"missing"、または"unknown" のいずれか
curve	string	いいえ	"P-256"、"P-384"、"P-521"、または"secp256k1" のいずれか
hash	string	いいえ	"SHA-256"、"SHA-384"、または"SHA-512" のいずれか
signatureBytes	integer	いいえ	0 以上
verifiableHere	boolean	はい	Whether POST /v1/jwt/verify can check this token.
summary	string	はい

Error

The error envelope of every non-2xx response.

フィールド	型	必須	説明
error	object	はい
error.code	string	はい	Machine-readable error code. Each response lists the codes it can carry; new codes may be added within v1, so treat an unknown code by its HTTP status.
error.message	string	はい	Human-readable explanation (English).
error.requestId	string	いいえ	The X-Request-Id of this request — quote it when reporting a problem. Sent since v1.1.
error.detail	object	いいえ	Structured context for the error, such as the offending field; omitted when there is none. メンバー名は任意
error.docs	string	いいえ	Where the error codes are explained. Sent since v1.1. 形式 uri

すべての操作は API リファレンスに掲載しています。