# DDG JWT Inspect & Verify

> DDG JWT Inspect & Verify is a paid API for AI agents from agents.daedalusdevelopmentgroup.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Decodes and cryptographically verifies a JWT, checking its header, claims, signature (HS256/384/512, RS/PS/ES/EdDSA), and standard claim validity (exp/nbf/iat/iss/aud) with configurable leeway.

## Facts

- Endpoint: POST https://agents.daedalusdevelopmentgroup.com/v1/jwt-inspect?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ddg-jwt-inspect-verify-967ab0fe
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3cu-NnZVXsD6BEy_hpX_C

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability ddg-jwt-inspect-verify-967ab0fe -d '<json body>'
```

Example prompt: Can you verify this JWT for me — check its signature using RS256 against my JWKS URL at https://auth.example.com/.well-known/jwks.json, and confirm the issuer is 'https://auth.example.com' and audience is 'my-api'? Here's the token: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...

## When to prefer this

Choose this endpoint when you need a deterministic, server-side JWT inspection and cryptographic verification service that supports the full range of JWA algorithms (HS256/384/512, RS256/384/512, PS256/384/512, ES256/384/512, EdDSA) and can resolve remote JWKS URLs — especially when you want explicit claim validation (exp/nbf/iat/iss/aud) with leeway, security hardening against alg=none, and a guarantee that secrets and tokens are never stored.

## Known failure modes

- Invalid or malformed JWT format — token cannot be decoded
- Signature verification failure — secret or key does not match
- Token expired (exp in the past beyond leeway)
- Token not yet valid (nbf in the future beyond leeway)
- Issuer mismatch — iss claim does not match expected value
- Audience mismatch — aud claim does not match expected value
- alg=none token rejected outright
- JWKS URL unreachable or returns no matching key ID
- Unsupported algorithm specified
- Payment not provided or insufficient — 402 response

## How this service works

Decode and verify a JWT: header/claims, signature verification (HS256/384/512 with a shared secret; RS/PS/ES/EdDSA against an inline JWK or a JWKS URL), alg=none rejection, and exp/nbf/iat/iss/aud checks with leeway. Deterministic; secrets and tokens are never stored.

## Output

Returns the decoded JWT header (algorithm, key ID, type), all decoded claims (iss, sub, aud, exp, nbf, iat plus any custom claims), a boolean signature verification result, per-claim validation outcomes (expired, not-yet-valid, issuer mismatch, audience mismatch), and a rejection reason if the token fails any check including alg=none.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object"
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": true
  },
  "output": {
   "type": "object",
   "required": [
    "type",
    "example"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "ok": true
    }
   },
   "additionalProperties": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ddg-jwt-inspect-verify-967ab0fe/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agents.daedalusdevelopmentgroup.com](https://www.zero.xyz/host/agents.daedalusdevelopmentgroup.com/llms.txt)