Who can use this feature? PayBox is available globally. You don't need a MoonPay account — PayBox is a standalone product with its own onboarding.
Overview
PayBox sits between your credentials and the agents that want to use them. Instead of giving an agent your raw card number, wallet key, or password, you create a scoped agent client in PayBox. The agent talks to PayBox; PayBox enforces your rules and returns scoped credentials.
This article explains the concepts that underpin every agent connection — agent clients, grants, client keys, and how requests flow.
Tip: For details on how the credentials themselves are protected, see PayBox: store credentials once, let AI agents pay securely.
What's an agent client?
An agent client is the identity PayBox uses to authenticate and authorize a specific agent. Think of it as a named profile for each agent that needs access to your credentials.
You might have one agent client for your trading bot, another for a personal assistant, and another for a research workflow. Each one has its own permissions, approval rules, and audit trail. Revoking one doesn't affect the others.
Note: One agent client per agent. Sharing a client across multiple agents makes the audit log harder to interpret and makes revocation an all-or-nothing decision.
Grants and client keys
Two things make an agent client functional: a grant and a client key.
The grant
A grant defines what the agent client is allowed to do. When you create an agent client, you choose:
Which credentials the agent can request (specific wallets, cards, or secrets — not all of them)
What operations are allowed (signing transactions, requesting payment tokens, accessing named secrets)
What scope limits apply (spend limits, allowed merchants, allowed chains, allowed contracts)
Which approval mode the client runs in (always approve, approve above limit, or autonomous within policy)
The grant is the source of truth PayBox checks against on every request.
The client key
The client key is the secret the agent uses to authenticate with PayBox. It's how PayBox knows the request is coming from the agent client you set up, not someone else.
Important: Treat the client key like a password. Anyone who has it can make requests to PayBox as that agent client — though they still can't act outside the grant you've set, and high-risk operations will still trigger your approval.
How a request flows
Every credential request follows the same shape:
Your agent sends an operation request to PayBox using its client key
PayBox authenticates the client key
PayBox checks the request against the agent client's grant
If the request is allowed automatically, PayBox executes it and logs the event
If approval is required, PayBox creates a pending approval and notifies you
You approve or deny with passkey or biometric step-up
If approved, PayBox executes exactly the approved operation and returns the result
The agent never sees your underlying credential for cards and wallets — it receives a derived output like a scoped payment token or a transaction signature. For secrets, the raw secret is returned according to your grant rules.
What agents can do — and what they can't
What they can do
Request payment tokens or one-time virtual cards for transactions you've authorized
Request signatures or transaction broadcasts for wallet operations within your grant
Retrieve secrets you've explicitly provisioned to them
Operate autonomously inside a tightly defined policy you've pre-authorized
What they can't do
See your raw card number, wallet private key, seed phrase, or MPC share
Act outside the grant you've configured
Change the details of a pending approval after you've reviewed it
Continue operating after you've revoked their access
Move money through PayBox itself — PayBox issues credentials, but funds move directly between your funding source and the merchant or recipient
Supported agent platforms
PayBox is platform-neutral. Any agent that can hold an API key and make HTTPS requests can connect to it. In practice, that includes most production AI agent platforms and any custom agent you build yourself.
For integration details and code samples, see the PayBox developer documentation.
Tip: Start with a narrowly scoped grant — one wallet, one approval mode, a low spend limit — and expand as you build trust in how the agent behaves. You can always widen a grant later. Tightening one is easier when there's less to undo.
Revoking an agent connection
You can revoke an agent client's access at any time from the PayBox dashboard. Removing a client's grant immediately prevents it from making further requests. The agent's client key becomes useless once revoked.
For a full lock on all agent access at once, use the kill switch in your PayBox account settings.