jwtpeek

Decode and inspect a JWT in your terminal. See the header, the payload, and a human-readable expiry verdict — without pasting your token into a website. Zero dependencies, fully offline, nothing uploaded.

npx jwtpeek eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Header
  {
    "alg": "HS256",
    "typ": "JWT"
  }

Payload
  {
    "sub": "1234567890",
    "name": "John Doe",
    "iat": 1516239022
  }

Claims
  issued   2018-01-18 01:30:22 UTC  8y 150d ago

Why

Debugging auth means constantly asking "what's actually in this token, and has it expired?" The usual answers are bad: paste it into jwt.io (your token — often a live credential — now lives in a browser tab and maybe a third party's logs), or hand-assemble a pipeline nobody remembers:

echo "$TOKEN" | cut -d. -f2 | base64 -d 2>/dev/null | python -m json.tool   # and base64 -d vs -D differs across macOS/Linux…

jwtpeek is one command. It runs entirely on your machine, makes no network requests, and prints the time claims (exp, iat, nbf, …) as real dates plus "expires in 3h 21m" / "EXPIRED 2d ago".

Decode, not verify — read this

jwtpeek never checks the signature. It shows you what a token says, not whether it's authentic. Anyone can forge a token that decodes cleanly. Never trust decoded contents for an authorization decision — verify the signature against the issuer's key first (that needs a secret/public key, which is out of scope for a decoder).

Usage

jwtpeek <token>            # header, payload & expiry (human-readable)
jwtpeek <token> --json     # {header, payload, signature, expired, notYetValid}
jwtpeek <token> --header   # only the decoded header (JSON)
jwtpeek <token> --payload  # only the decoded payload (JSON)

pbpaste | jwtpeek          # read the token from stdin
echo "$AUTH_HEADER" | jwtpeek   # a leading "Bearer "/"Authorization:" is stripped

Pipe-friendly: the decoded output goes to stdout, the "not verified" safety note goes to stderr, so jwtpeek "$t" --json | jq .payload stays clean.

Scripting with the exit code

0   decoded OK and not expired (or no exp claim)
1   decoded OK but the token is expired
2   not a valid JWT (decode error)

jwtpeek "$TOKEN" >/dev/null 2>&1 && echo "still valid" || echo "expired or invalid"

Install

npm install -g jwtpeek     # then: jwtpeek <token>
# or just run it once:
npx jwtpeek <token>

Requires Node ≥ 18. There is also a byte-for-byte Python port: pip install jwtpeek (jwtpeek-py).

License

MIT