# Virtual cards for AI agents: what limits actually exist

Nine card options for AI agents compared on what they actually enforce: spend limits, merchant locks, single-use cards, real-time approval, who can sign up, and cost. Checked 19 October 2026.

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## Options compared (checked 19 October 2026; ordered by fit for a small operator)

- **Privacy.** Who can get it: US citizens or legal residents, 18+, with a US checking account. Spend limits: Per transaction, monthly, yearly or total, on each card. Locks and single-use: Merchant-locked and single-use cards on every plan; category-locked from Plus. Real-time approval: No. Its webhooks report transactions but cannot approve or decline them. Cost: Personal $0 (12 new cards a month). Plus $5 a month adds API access, which its MCP server and CLI connect to. 3% foreign fee on Personal and Plus.
- **Mercury agent cards.** Who can get it: Mercury Business customers. The company must be formed and registered in the US or a US territory. Spend limits: Daily, weekly or monthly per card. Only a person sets or changes it, in the app. Locks and single-use: The agent can read only the cards you give it. It cannot create cards, raise limits or unfreeze. Real-time approval: not stated Cost: Banking plan $0 a month.
- **Ramp.** Who can get it: Businesses. The Ramp corporate card is issued in the US and subject to credit approval. Spend limits: Per transaction, day or month on each virtual card. Locks and single-use: Lock a card to one vendor or merchant category. Single-use cards close after one payment. Real-time approval: Its agent tools add a budget, merchant limits and a human approver before money moves. Cost: Free plan $0 per user a month, unlimited cards.
- **Brex.** Who can get it: Businesses (corporate card). Spend limits: Custom spend limits on each card. Locks and single-use: Category and merchant controls. Vendor cards can be set to recur or expire. Real-time approval: Purchase cards offer PO-style approval flows. Cost: Essentials $0 per user a month, with API access. Premium $12 per user a month.
- **Stripe Issuing (Issuing for agents).** Who can get it: Businesses in the US, UK and many EEA countries, after an eligibility review. Spend limits: Per authorization, daily, weekly or monthly. Unset cards default to $500 a day. Standard programs also cap $5,000 a week. Locks and single-use: Allowed or blocked categories and merchant countries. Single-use or n-use cards through lifecycle controls. Real-time approval: Yes. A webhook approves or declines each authorization; no answer in 2 seconds falls back to your timeout setting. Cost: $0.10 per virtual card.
- **Lithic.** Who can get it: Companies building their own card program on its API. Spend limits: Per transaction, monthly, yearly or lifetime on each card. Locks and single-use: Single-use and merchant-locked card types. Allow or block merchant categories with authorization rules. Real-time approval: Yes. Auth Stream Access sends each authorization to your endpoint; no answer in 6 seconds is a decline. Cost: No public price list.
- **AgentWallet.** Who can get it: Invite-only. Spend limits: Per transaction, per hour, per day, and per merchant per day. Locks and single-use: Rules by merchant category, merchant, country and channel. Real-time approval: not stated Cost: No published price.
- **Naïve.** Who can get it: Customers of the Naïve agent platform. Spend limits: A hard cap on each card that the agent cannot raise, according to Naïve. Locks and single-use: Unknown merchants are declined. Real-time approval: not stated Cost: $20 or $200 a month with credit included, after a 7-day trial with $5 of credit.
- **AgentCard.** Who can get it: Apps that let their users’ agents buy, rather than one operator. Spend limits: Purchases auto-approve within limits the customer sets. Locks and single-use: One-time or multi-use cards on the Issuing plan. Real-time approval: Passkey approval before a stored card pays (Vault). Cost: Vault free up to 5,000 users. Issuing $5,000 a month plus a 1% revenue share.

## Setup checklist

1. **Pick the cap first.** Decide the most you would accept losing on this one job. The agent spend-cap calculator gives a per-transaction and daily starting point.
2. **One card per agent and job.** A separate card for each task lets you freeze one without touching the rest.
3. **Set the limit before the agent sees the number.** Per transaction plus a daily or weekly window, not an open monthly cap.
4. **Lock it to where it should spend.** Merchant-locked, single-use, or allowed categories, where the provider offers them.
5. **Keep admin power with a person.** Card details go in the agent’s secret store or the provider’s vault, never in chat. The agent never gets your admin login or secret API key.
6. **Test small, then review.** Run one small purchase first, check the receipt, then review weekly and freeze the card at the first odd charge.

## FAQ

**What is a virtual card for an AI agent?**
A card number that exists only online and is issued for one agent. It has its own limit and can be frozen or closed alone, so a mistake can cost no more than that card allows.

**Can the agent raise its own limit?**
It depends on the setup. Mercury says agents cannot create agent cards, raise limits or unfreeze them. With a card API such as Stripe Issuing or Lithic, anything holding your secret API key can change limits, so the agent must never hold it.

**Does a real-time approval webhook mean I approve each purchase by hand?**
No. Stripe waits 2 seconds for an answer and Lithic 6 seconds, so your own code decides, not a person. If you want a human yes or no before the agent spends, have it ask first; see ping, don’t spend.

**Is a prepaid card the same thing?**
Not quite. A prepaid card spends money loaded onto it. Most cards here draw from your account per purchase and stop at the limit you set. Either way, the limit is what stops the agent.

## Sources (checked 19 October 2026)

- Privacy — pricing and plan comparison: https://www.privacy.com/pricing
- Privacy — Who can use Privacy?: https://support.privacy.com/hc/en-us/articles/360012046934-Who-can-use-Privacy
- Privacy — AI agents (MCP and CLI): https://agents.privacy.com
- Privacy Developer API — Transaction webhooks: https://developers.privacy.com/docs/transaction-webhooks
- Mercury — Agent cards: https://support.mercury.com/hc/en-us/articles/51299754284948-Agent-cards-Giving-AI-agents-a-card-of-their-own
- Mercury — Eligibility and requirements: https://support.mercury.com/hc/en-us/articles/28770467511060-Eligibility-and-requirements-for-opening-a-Mercury-account
- Mercury — pricing: https://mercury.com/pricing
- Ramp — virtual cards: https://ramp.com/virtual-cards
- Ramp — pricing: https://ramp.com/pricing
- Ramp — finance for agents: https://agents.ramp.com
- Brex — corporate cards: https://www.brex.com/product/corporate-cards
- Brex — pricing: https://www.brex.com/pricing
- Stripe — Issuing for agents: https://docs.stripe.com/issuing/agents
- Stripe — Issuing spending controls: https://docs.stripe.com/issuing/controls/spending-controls
- Stripe — Issuing real-time authorizations: https://docs.stripe.com/issuing/controls/real-time-authorizations
- Stripe — Issuing lifecycle controls: https://docs.stripe.com/issuing/controls/lifecycle-controls
- Stripe — Issuing for your business (standard program limits): https://docs.stripe.com/issuing/for-your-business
- Stripe — How Issuing works (availability): https://docs.stripe.com/issuing/how-issuing-works
- Stripe — pricing (Issuing): https://stripe.com/pricing
- Lithic — Spend limits: https://docs.lithic.com/docs/spend-limits
- Lithic — Auth Stream Access (ASA): https://docs.lithic.com/docs/auth-stream-access-asa
- Lithic — Create card API (card types): https://docs.lithic.com/reference/postcards
- Lithic — Merchant category codes in authorization rules: https://docs.lithic.com/docs/merchant-category-codes-mccs
- AgentWallet — virtual card: https://agentwallet.ai/virtual-card/
- Naïve — cards: https://usenaive.ai/blog/introducing-cards
- Naïve — pricing: https://usenaive.ai/pricing
- AgentCard — pricing: https://agentcard.com/pricing
- Visa — Visa Intelligent Commerce: https://corporate.visa.com/en/products/intelligent-commerce.html
- Mastercard — Agent Pay: https://www.mastercard.com/us/en/business/artificial-intelligence/mastercard-agent-pay.html

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Related: [AI agent spending limits](https://agentlane.net/guides/agent-spend-caps/)