Concepts and protocols
Virtual cards for AI agents: how do they work?
How issuing a virtual card to an agent works, which spending controls card issuers like Stripe Issuing offer, and where card limits fall short.
You issue a separate virtual card for the agent through a card-issuing platform and set controls on it: spending limits per authorisation or per period, allowed or blocked merchant categories and countries, and optionally a real-time decision on each authorisation.
Why is this harder than it sounds?
Cards work almost everywhere, which is their appeal for agents shopping on the open web. But card controls were designed for employees, not software. They limit spend by category and period rather than by intended payee, aggregation can lag, and tips or later adjustments can push a charge past a limit. The agent also has to handle the card details themselves, which puts a spendable credential in its context unless something tokenises it.
How do you do it?
- Issue one card per agent. A dedicated card makes every charge attributable and lets you freeze one agent without affecting others.
- Set spending limits. Stripe Issuing's spending_controls takes spending_limits with an amount and an interval, for example per_authorization, weekly or monthly. If you set none, Stripe applies a default of 500 USD per day to new cards.
- Narrow where it can be used. Use allowed_categories or blocked_categories for merchant categories, and allowed_merchant_countries or blocked_merchant_countries.
- Decide in real time if you need to. With real-time authorisations, your server receives an issuing_authorization.request webhook and approves or declines each charge.
- Know the edges. Stripe notes spend aggregation is best effort with a delay of up to 30 seconds, and that tips and fees posted later can exceed a limit.
What it does not mean
- A virtual card isn't a prepaid balance by default. What it can spend depends on the limits and the funding behind it.
- Merchant category limits aren't payee limits. An allowed category still includes every merchant in it.
- Putting card details in the agent's prompt is the card equivalent of handing over a private key.
Common questions
Can an agent use a card without seeing the number?
Tokenised approaches such as Stripe's Shared Payment Tokens let an agent use a customer's payment method through a scoped grant instead of raw card details.
Is this financial advice?
No. It describes how card controls work, not which provider or product to use.
Where does Veyra fit?
Veyra doesn't issue cards. It controls payments from a crypto wallet you connect, in USDC on Base, with limits per payment and per day, an auto-approve band, an approval band, and a recipient allowlist by address, which is the payee-level control cards don't offer. If your agent needs to pay merchants that only take cards, a card-issuing platform is the right tool; Veyra suits payees that accept USDC on Base.
Sources
Terms on this page
- Shared Payment Token (SPT)A Shared Payment Token (SPT) is a Stripe credential that grants an agent or seller scoped use of a customer's payment method, such as a card, with usage and expiration limits.
- Auto-approve limitAn auto-approve limit is the largest single payment an agent may make without a person approving it, within any other caps that apply.
This page explains how agent payments and the related technology work. It is not financial, investment, legal or tax advice. Protocols and provider features change; check the linked official sources before relying on a detail.