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$ man jwt-decode

/jwt-decode

agentutility / web-probe / jwt-decode
PRICE / CALL
$0.003
USDC · base mainnet · scheme: exact
METHOD
POST
CLUSTER
webprobe
CATEGORY
utilities
STATUS
live
NAME
jwt-decode decodes a jwt and inspects its claims without needing the signing key
SYNOPSIS
POST https://x402.agentutility.ai/jwt-decode
     Content-Type: application/json
     X-PAYMENT:    <signed-transferWithAuthorization>

     { ... }
↳ first call → 402 Payment Required. Sign USDCtransferWithAuthorization, retry with theX-PAYMENT header.
DESCRIPTION

Decodes a JWT and inspects its claims without needing the signing key. Base64URL-decodes header and payload, parses standard claims (iss, aud, sub, exp, iat, nbf, jti), and reports algorithm, key id (kid), token type (typ), TTL, and clock-validity (is_expired / is_not_yet_valid / is_currently_valid_by_clock). Does NOT verify signatures — for inspection only, never trust output for auth decisions. Use it as a JWT parser, JSON Web Token inspector, Bearer token debugger, OAuth ID-token reader, or Auth0 + Cognito + Firebase token inspector.

INPUTrequest schema
propertytypedescriptionreq?
jwtstringCompact-serialization JWT string (three base64url segments separated by '.'). May be prefixed with 'Bearer ' — that prefix is stripped automatically.required
OUTPUTresponse shape
fieldtypedescription
headerobjectDecoded JWT header object with parsed JOSE fields like alg, typ, kid, and any custom header parameters.
payloadobjectDecoded JWT payload object with all claims parsed from the base64url-decoded middle segment.
signaturestringRaw signature segment from the JWT as a base64url string; not verified by this endpoint.
algorithmstringSigning algorithm declared in the header's alg field, such as HS256, RS256, ES256, or none.
key_idstringKey identifier from the header's kid field, used by verifiers to select the right signing key.
typestringToken type from the header's typ field, typically JWT but sometimes at+jwt or similar variants.
claimsobjectStandard JWT claims extracted from payload: iss, aud, sub, jti, iat, exp, nbf with parsed timestamps.
is_expiredbooleanTrue if exp claim is present and the expiration timestamp is in the past relative to server clock.
is_not_yet_validbooleanTrue if nbf claim is present and the not-before timestamp is in the future relative to server clock.
is_currently_valid_by_clockbooleanTrue if the token is neither expired nor not-yet-valid by clock; signature validity is not checked.
payload_size_bytesnumberByte length of the decoded payload JSON, useful for spotting oversized tokens.
notestringReminder that this endpoint only decodes and clock-checks; it does not cryptographically verify signatures.
EXAMPLEStwo ways to call
EXAMPLE 1 · curl
curl -X POST https://x402.agentutility.ai/jwt-decode \
  -H 'Content-Type: application/json' \
  -d '{ }'
first response = 402 Payment Required with payment requirements; sign + retry with X-PAYMENT.
EXAMPLE 2 · mcp
# Install the MCP package for this endpoint's cluster
npx -y @agentutility/mcp-<cluster>

# Required: EVM private key with USDC on Base
export X402_PRIVATE_KEY=0x...

# Then call the jwt-decode tool from your MCP-aware agent.
MCP server handles payment automatically — your coding agent just calls the tool by name.
METADATA
tags
jwttokenauthdebugdeveloper
methods
POST
cluster
webprobe
price
$0.003 USDC per call
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SEE ALSO
agentutility · webprobe · x402 · mcp · llms.txt · registry.json · bazaar.x402.org