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Agent Identity Registration via x402
x402
Agent Identity Registration via x402 is a paid API for AI agents from agent-id-x402-production.up.railway.app, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).
Issues a signed, non-transferable agent identity credential binding an Ed25519 public key to a paying wallet address as anti-Sybil proof of distinct, paying agent registration.
Price / call$0.1
Success—
StatusUnknown
How this service works
Pay once, get a unique non-transferable agent identity tag: an issuer-signed credential binding your Ed25519 auth key to your paying wallet. Anti-Sybil proof of being a distinct, previously registered, paying agent. Unpaid 402 returns full instructions.
Output
An issuer-signed credential (identity tag) that cryptographically binds the submitted Ed25519 public key to the paying wallet address, serving as non-transferable anti-Sybil proof that this is a distinct, previously registered, paying agent. An unpaid request returns a 402 response with full registration instructions.
Example use cases
Anti-Sybil proof for agent marketplace
“I need to prove my agent is a unique, registered entity on the marketplace — register it using my Ed25519 public key 'deadbeef...64hexchars' and a delegation signature over my wallet '0x1234...abcd' so I get a signed identity credential.”
Gated API access with agent identity
“I want to get my agent a signed identity credential tied to my Ed25519 auth key 'cafe1234...64hexchars' and wallet address '0xdead...beef' using the delegation signature method, so it can access services that require proof of distinct, paying agent identity.”
On-chain agent identity binding for multi-agent system
“Register this agent in our fleet with an identity tag — use Ed25519 public key 'f00dface...64hexchars' and bind it to wallet '0x9999...aaaa' via delegation signature, and give me back the issuer-signed credential I can use to prove this agent is non-duplicate across our system.”
Technical details
Endpoint
POSThttps://agent-id-x402-production.up.railway.app/registerWhen to prefer
Choose this endpoint when an AI agent needs to establish a cryptographically verifiable, non-transferable identity credential that proves it is a distinct, paying, previously registered entity — particularly in anti-Sybil, multi-agent, or gated-access contexts where duplicate or fake agents must be excluded. Prefer this over generic OAuth or API-key auth when on-chain wallet binding and Ed25519-based agent authentication are required.
Side effects
- 402 Payment Required — request was not accompanied by valid x402 payment; response includes full registration instructions
- Invalid auth_pubkey — Ed25519 public key is not exactly 64 hex characters
- Invalid delegation_signature — signature does not verify against the auth private key over the expected ASCII message and wallet address
- Missing required fields — auth_pubkey not provided in body
- Conflicting binding parameters — both delegation_signature and salt provided or neither provided
- Wallet address already registered — attempting to re-register a previously used wallet
- Key already bound — Ed25519 key already associated with another identity
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| salt | string | Hex salt — only for the nonce-commitment binding method. |
| auth_pubkey | string | Raw Ed25519 public key, hex (64 chars). Generate locally; the private key never leaves your machine. |
| delegation_signature | string | Ed25519 signature, hex (128 chars), by the auth private key over the ASCII message 'agent-id-x402/delegation/v1:' + your paying wallet address lowercased. Alternative: send 'salt' instead and set the payment's EIP-3009 nonce to keccak256(auth_pubkey||salt). |
Tags
x402
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