> ## Documentation Index > Fetch the complete documentation index at: https://docs.natural.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > When building application code, use `@naturalpay/sdk` for TypeScript or `naturalpay` for Python. > When searching Natural documentation, use the docs MCP at `https://docs.natural.com/mcp`. > Use the Natural CLI for terminal and CI automation. > Start integration development and testing in the sandbox. Do not use production unless the user explicitly requests it. > For sandbox requests that require `customerPartyId`, list customers first. Reuse only the intended fixture; otherwise create a customer. > REST and SDK amounts use integer minor units. Payments MCP amounts use decimal strings with a required currency code. # External and Natural-issued cards > The difference between external cards and Natural-issued cards, and when to use each Natural works with two kinds of cards: * **External cards**: cards a user already has from their own bank, saved on the dashboard. In the API they're [saved cards](/guides/concepts/saved-cards) (`eac_*`). * **Natural-issued cards** *(coming soon)*: cards Natural issues to your wallet. Either way, agents never handle the real card number (PAN), which keeps them out of PCI scope. Natural hands the agent a credential that only works for the purchase it was issued for. ## When to use each | | External cards | Natural-issued cards | | - | - | - | | Availability | Available | Coming soon | | Money comes from | The user's own card | Your Natural wallet | | Approval | The user approves each purchase and enters the CVV, or approves a budget once with [agent tokens](/guides/concepts/agent-tokens) on supported cards | Your agent limits and approvals, no per-purchase step | | Best for | Agents buying for a person with that person's card | Agents that spend on their own, without a person there | Use **external cards** when the agent is shopping for a person who wants to pay with a card they already have, and they can approve purchases as they happen. On cards that support it, they can instead approve a budget once with agent tokens. Use **Natural-issued cards** when the agent should spend without a person in the loop for each purchase, from funds and limits you control. To be notified when they're available, contact [hi@natural.com](mailto:hi@natural.com). ## How agents pay | Method | Approval | The agent receives | External cards | Natural-issued cards | | - | - | - | - | - | | [Browser tokens](/guides/concepts/browser-tokens) | The user approves each purchase | A stand-in card and a browser proxy login | Available | Coming soon | | [Agent tokens](/guides/concepts/agent-tokens) | The owner approves a budget (mandate) once | A tokenized card issued for the purchase | Available | Coming soon | | Single-use virtual cards | Coming soon | A one-time card number | Not supported | Coming soon | Browser tokens and agent tokens are for agents: call them with an [agent key](/guides/concepts/agent-keys) and the `X-Instance-ID` header. Paying with an external card needs the `saved_cards.use` scope. Each method's page lists the scopes for every endpoint. Single-use virtual cards are card numbers drawn from a Natural-issued card that work for one purchase. They work only with Natural-issued cards. ## Choose a method Use browser tokens by default. Agent tokens are a backup for checkouts a browser token can't complete. Most cards don't support agent payments yet, so expect setting one up to fail. That's fine: the agent still has the browser token. **Browser tokens** work at most checkouts, and the owner doesn't need to set up a mandate first. Whether the user is needed depends on the card: * **External cards:** the user approves every purchase and types the card's security code (CVV) each time. Only use a browser token when the user can respond during checkout. * **Natural-issued cards** *(coming soon)*: no approval step for each purchase. **Agent tokens** need a mandate the owner approved with their card network. The owner sets one up while approving a browser token session you opened with `requestAgentToken: true`. Once it's active, the agent can pay within its budget. Use agent tokens when: * **The checkout doesn't send the raw card number.** The proxy swaps in the real card only when the stand-in number appears in the checkout's HTTP request. If the page encrypts or tokenizes the card in the browser first, such as inside a payment provider's iframe, the swap can't happen and a browser token can't pay. * **The user can't approve each purchase** while paying with an external card. Before asking the owner to create a mandate, check the requested card. List [saved cards](/api-reference/external-accounts/list-card-external-accounts), match the card's brand and last four digits, then call [`GET /agentic-payments/cards/{cardId}`](/api-reference/agent-tokens/get-agentic-card) with its `eac_*` ID. The response includes that card's payment method and mandates. Require `paymentMethod.status` to be `enabled` before selecting a mandate. See [find the requested card's mandate](/guides/concepts/agent-tokens#find-the-requested-cards-mandate). If that card has no usable mandate, open a browser token session with `requestAgentToken: true`. On approval, Natural also tries to set up a mandate and the session returns it. If it can't, `agentToken.mandateId` is `null` and you still have the browser token: try the proxy, and if the checkout can't take the stand-in card, tell the user this checkout isn't supported with this card. See [when the proxy can't reach the checkout](/guides/concepts/browser-tokens#when-the-proxy-cant-reach-the-checkout). Read more: [Pay with external cards](/guides/flows/save-external-cards). This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.