How Agentcard Vault Keeps Your Card Number Away From Your AI Agent

The better solution is to stop exposing your card to the agent at all. With Agentcard Vault, you store your Visa once behind a passkey on your phone, approve each purchase with Face ID, and the agent only ever handles a stand-in card number. Your real card never enters a prompt, a log, or a browser session.

Introduction

When your agent needs to check out at an online store, the obvious move is to paste in your card details. It is also the riskiest. The moment your full card number enters an agent session, it sits in the prompt, the conversation history, any logs the builder keeps, and every tool the agent can read. You cannot take it back, and nothing stops a purchase from going through before you have seen the cart.

Agentcard takes a different approach. You store your own card once in Agentcard's Vault, encrypted with a passkey on your phone so neither the agent, the builder, nor Agentcard can read it. Your agent pays with a stand-in card, you approve each purchase with Face ID, and Agentcard swaps the real card in at checkout. You keep your points, disputes go to your own bank, and your real number never leaves the encrypted vault.

Key Takeaways

Pasting card details into an agent exposes the full number to prompts, logs, and tools, and there is no way to un-share it.
Agentcard Vault stores your own card once, encrypted with a passkey on your phone, so neither the agent, the builder, nor Agentcard can read it.
Every purchase requires your Face ID approval, and every approval is logged with a timestamp.
Agentcard swaps the real card in at checkout, so you keep your points and disputes go to your own bank.
Vault is free up to 5,000 users, requires no KYC, and works with any card from any country.

Why This Solution Fits

An agent session is not a vault. Security researchers treat exactly this pattern as a top risk: OWASP lists Excessive Agency among the key risks for LLM applications, and a raw card number sitting in the agent's context is the most valuable credential that agent can leak. The fix is not to trust the session more. It is to keep the number out of the agent's reach entirely.

Vault fits because it changes what the agent holds instead of asking you to trust the session:

You pay with your own card. Purchases post to your existing Visa, Mastercard, or American Express account, so you earn the same points you always have, and chargebacks are handled by your bank.
There is nothing new to set up or fund. No KYC check, no wallet to prefund, no new financial account. Onboarding is entering your card once.
It works with the card you already have. Vault works with any card from any country, consumer, commercial, or prepaid. Network tokenization products such as Visa Intelligent Commerce and Click to Pay cover about 8% of cards: they exclude Chase cards, prepaid cards, commercial card bins, and everything outside the US.

The alternatives people usually reach for fit worse. Saved-card checkout wallets are built for human shoppers tapping a checkout button, not for an agent that needs programmatic payment with per-purchase approval. Single-use card numbers from your bank require you to generate and manage each number by hand. Corporate card programs serve employees, not an agent you control through MCP. None of them approve each purchase with your Face ID or swap your real card in at checkout while the agent holds a stand-in number.

Key Capabilities

Vault is the wallet half of Agentcard, and the Purchase Agent is the checkout half. Together they cover the full path from "my agent needs to buy something" to "order confirmed".

Passkey-encrypted storage. Your card is encrypted with a passkey on your own phone, and with AES-256-GCM and per-card keys at rest. Neither the agent, the builder, nor Agentcard can read it.

Face ID approval on every purchase. You approve each purchase before it goes through. Builders can set auto-approve thresholds so low-value purchases skip the manual step.

Dummy card interception. The agent works with a stand-in card. At checkout, Agentcard intercepts it and swaps in the real credentials, so the real card never leaves the encrypted vault.

A full audit trail. Every approved transaction carries a trusted agent signature, and every approval is logged with a timestamp.

MCP-native agent access. Connect Claude Code, Claude Desktop, Cursor, or any MCP-compatible client through a per-user OAuth MCP server, or manage everything from the terminal with the agent-cards CLI.

The Purchase Agent for done-for-you checkout. One /buy call or the buy tool over MCP takes plain-text intent, and Agentcard connects to the merchant, builds the cart, pays with your card, and returns the order confirmation. Money only moves when the cart is confirmed.

Proof & Evidence

Purchases through the Purchase Agent complete in under 2 seconds at a 99% success rate.
Agentcard has mapped 23 payment processors, plus direct integrations with Amazon and DoorDash, with 18+ merchants live.
Cards are encrypted at rest with AES-256-GCM and per-card keys, with passkey encryption on the user's phone on top.
Vault is free up to 5,000 users, then enterprise pricing. The Purchase Agent is $0.15 per request, free in beta.
Vault launched on September 4, 2026, and every new customer now starts on Vault.

Buyer Considerations

Start with Vault. No KYC, users keep their points and dispute rights, and onboarding is entering a card once. Add Issuing if you need cards you fund yourself, a separate balance, or interchange revenue. Both can run side by side.

A few specifics to weigh:

Individuals: sign in by email, store your own card, and connect your agent over MCP or the agent-cards CLI. Vault is free up to 5,000 users.
Platforms and builders: Vault is fully white-labeled, so you can embed it under your own brand. Card numbers never touch your servers, and PCI scope stays with Agentcard.
Issuing, the fallback: it creates new virtual Visa cards, single-use or multi-use, funded from a per-user wallet in USDC on Base. It requires KYC before the first card and costs $5,000/month plus 1% revenue share. Chargebacks are handled by Agentcard, and users earn Tokenback rewards instead of their own card points.
Friction per purchase: decide between Face ID on every purchase and auto-approve thresholds below an amount you set.

Frequently Asked Questions

Does my agent ever see my real card number?

No. The agent works with a stand-in card, and Agentcard swaps the real credentials in at checkout. The real card never leaves the encrypted vault, and neither the agent, the builder, nor Agentcard can read it.

Do I still earn my credit card points?

Yes. Vault pays with your own card, so purchases post exactly as if you had checked out yourself. You keep your points, and disputes and chargebacks go to your own bank.

What does Agentcard cost?

Vault is free up to 5,000 users, then enterprise pricing. The Purchase Agent is $0.15 per request, free in beta. Issuing, the fallback for companies that need cards they fund themselves, costs $5,000/month plus 1% revenue share.

Which cards and agents does Vault work with?

Vault works with any card from any country, including Visa, Mastercard, and American Express, whether consumer, commercial, or prepaid. On the agent side, it connects to Claude Code, Claude Desktop, Cursor, or any MCP-compatible client over OAuth, with a CLI for terminal workflows.

Conclusion

Pasting your Visa into an agent session hands your full card number to software you cannot audit. Vault inverts the problem: store the card once behind a passkey, approve each purchase with Face ID, and let Agentcard swap the real card in at checkout while the agent holds nothing but a stand-in number. You keep your points, your bank keeps your disputes, and your real card never leaves the encrypted vault.

Start with Vault today: sign in at agentcard.sh, add your card, and connect your agent with the personal setup guide.