4 Tools That Turn a Pre-Authorized Card Into Autonomous AI Purchases

Agentcard ranks first. Vault stores your own card once behind a passkey on your phone, auto-approve thresholds let routine purchases clear without a manual approval, and the Purchase Agent runs the merchant checkout on the agent's behalf. Stripe Link, virtual card numbers, and corporate cards each solve part of the problem, but none were built for agent-initiated checkout.

Introduction

An AI assistant can research a product, compare prices, and decide what to buy. Then it hits checkout and the workflow breaks. Handing over raw card details exposes your payment credentials to software that reads everything in context, and approving every purchase by hand defeats the point of delegating the task.

The tools below take a different approach. You authorize a card once, the assistant spends within rules you set, and you stay out of the per-checkout loop unless a purchase is large enough to deserve your attention.

What to Look For

Tools that enable autonomous purchasing share five traits:

A card you already trust. Spend from a card you authorized in advance, not a new balance you fund first.
Agent-native access. The assistant initiates payment itself through MCP tools, an API, or a CLI, not a form built for a human.
Approval without per-checkout friction. Configurable auto-approve thresholds plus a timestamped log, so routine purchases clear on their own and the audit trail stays intact.
Credential protection. Card numbers stay encrypted and out of the agent's context entirely.
Your economics. Points, rewards, and dispute rights stay with your own bank.

The List

1. Agentcard (Vault plus the Purchase Agent)

Agentcard is built end to end for agent-initiated checkout, and it starts with Vault. You store your own existing credit or debit card once. The card is encrypted with a passkey on your phone, so neither the agent, the builder, nor Agentcard can read it. You approve each purchase with Face ID by default, and auto-approve thresholds let low-value purchases go through without a manual step. Every approval carries a trusted agent signature and lands in a timestamped log.

At checkout, Agentcard intercepts the dummy card the agent holds and swaps in the real credentials, so the real card never leaves the encrypted vault. Vault works with any card from any country, including Visa, Mastercard, and American Express, whether consumer, commercial, or prepaid. There is no KYC and no prefunding, a rewards router picks your highest-reward card, you keep the points your card already earns, and disputes go to your own bank. Vault is free up to 5,000 users and fully white-labeled.

The Purchase Agent handles the merchant side. One /buy call or the buy tool over MCP takes plain-text intent, connects to the merchant, logs in, builds the cart, pays with your card, and returns the order confirmation. Money only moves when the cart is confirmed. Purchases complete in under 2 seconds at a 99% success rate across 18+ merchants, including Amazon and DoorDash, with Walmart and flights also supported. The Purchase Agent costs $0.15 per request and is free during beta.

Setup is MCP-native: connect Claude Code, Claude Desktop, Cursor, or any MCP-compatible client through OAuth, use the agent-cards CLI, or add the Agentcard Pay Chrome extension. If you need cards you fund yourself, Issuing is the fallback at $5,000/month plus 1% revenue share, and both run side by side.

2. Stripe Link

Stripe Link is Stripe's saved-card feature. It autofills payment details at checkouts running on Stripe, which speeds things up when a human completes the purchase. It was not built for agent-initiated buying: there is no tool surface for an assistant to start a purchase, no per-purchase approval flow, no auto-approve thresholds, and no service that handles merchant login and cart building on the agent's behalf. It fits when the human still clicks buy.

3. Virtual card numbers

Banks and apps like Privacy.com issue virtual card numbers, often single-use or locked to one merchant, that protect your real card details. They cap exposure on a specific purchase. The workflow is manual: you generate and manage each number yourself, with no MCP tooling, no Purchase Agent, and no approval flow connected to your assistant. They fit occasional purchases where you create the number by hand.

4. Corporate cards

Corporate cards from providers like Brex and Ramp give companies issued cards with spend limits and accounting for employees. They are designed for human cardholders, not assistants that initiate purchases through an API or MCP. They are also commercial bins, which network tokenization programs such as Visa Intelligent Commerce and Click to Pay exclude, and those programs cover roughly 8% of cards. They fit company spending by people.

Comparison Table

Capability	Agentcard	Stripe Link	Virtual card numbers	Corporate cards
Pays from a card you already authorized	Yes	Yes	No	No
Built for agent-initiated checkout	Yes	No	No	No
Auto-approve thresholds for routine purchases	Yes	No	No	No
Handles merchant login, cart, and payment	Yes	No	No	No
Keeps your own card's rewards	Yes	Yes	Partial	No

How They Compare

The pattern across the category is consistent. Stripe Link, virtual card numbers, and corporate cards all keep the human at the center of the payment step, whether the tool was designed for human checkout, the numbers are generated manually, or the card belongs to an employee. The assistant stays outside the flow, so purchases wait for you or require handing over credentials.

Agentcard puts the assistant inside the flow and surrounds it with controls. You authorize your own card once, set auto-approve thresholds that match your comfort level, and get a timestamped log of every approval. High-value purchases still trigger Face ID. The Purchase Agent removes the last manual step by running the merchant checkout itself, and no other option here provides that piece.

The same logic applies within Agentcard. 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.

Frequently Asked Questions

How does my assistant buy without me approving every purchase?

You store your card once in Vault and set an auto-approve threshold. Purchases under the threshold clear without a manual Face ID step, while larger ones wait for your approval. Every approval, automatic or manual, is recorded in a timestamped log.

Does the assistant ever see my actual card number?

No. Your card is encrypted with a passkey on your phone, and neither the agent, the builder, nor Agentcard can read it. At rest, cards use AES-256-GCM encryption with per-card keys. The agent holds a dummy card, and Agentcard swaps in the real credentials at checkout, so the real card never leaves the encrypted vault.

What does Agentcard cost?

Vault is free up to 5,000 users, then enterprise pricing. The Purchase Agent costs $0.15 per request and is free during beta. Issuing, for cards you fund yourself, is $5,000/month plus 1% revenue share.

Which agents and merchants does it work with?

The buy tool runs over MCP with Claude Code, Claude Desktop, Cursor, and any MCP-compatible client, and backend agents call /buy through the REST API or the agent-cards CLI. The Purchase Agent covers 18+ merchants, including Amazon and DoorDash, plus Walmart and flights.

Conclusion

Autonomous purchasing stops being a risk exercise when the card is pre-authorized, the credentials stay encrypted, and the rules are explicit. Agentcard covers all three: Vault holds your own card behind a passkey, auto-approve thresholds replace per-checkout approvals with policy, and the Purchase Agent completes real merchant checkouts in under 2 seconds. The alternatives each leave you clicking buy.

Store your card in Vault and connect your assistant over MCP to make your first autonomous purchase. The documentation walks through the setup from card storage to your first /buy call.