> ## Documentation Index
> Fetch the complete documentation index at: https://next-developers.opencard.io/llms.txt
> Use this file to discover all available pages before exploring further.

# About OpenCard

> What OpenCard is, who uses it — EMS, card issuers, receipt providers — and what transaction, receipt, VAT, and environmental data lands in your webhooks.

OpenCard is the pipe between card programs and your app — transactions, receipts, VAT, line items, and environmental impact, pushed to your webhook as stuff happens.

No polling. No scraping PDFs.

## Who are you?

| You are...                       | Go here                                   | What you do                                                                                    |
| -------------------------------- | ----------------------------------------- | ---------------------------------------------------------------------------------------------- |
| 🏢 **Expense Management System** | [Quickstart](/getting-started/quickstart) | Create orgs, card holders, webhooks. Receive transaction events.                               |
| 💳 **Card issuer / bank**        | [Card Issuers](/card-issuers)             | Deliver transactions via the Issuer API, or fetch digital receipts via `receipts.opencard.io`. |
| 🧾 **Receipt provider**          | [Receipt Providers](/receipt-providers)   | Collect receipts, deliver to OpenCard for Expense Management System enrichment.                |

## The 30-second version

```mermaid theme={null}
sequenceDiagram
    participant Bank as Card Program
    participant OC as OpenCard
    participant You as Your Expense Management System

    Note over You,OC: Setup (once per client)
    You->>OC: Create billing profile (invoice recipient + line roll-up)
    You->>OC: Create TPA + signatories sign with eID
    You->>OC: Create organization + webhook (linked to billing)
    You->>OC: Create card holders

    Note over Bank,You: Runtime (every purchase)
    Bank->>OC: transaction data
    OC->>You: webhook card.transaction.*
```

## What you get pushed to your webhook

* `card.transaction.authorized` — purchase just happened
* `card.transaction.cleared` — settled, use for accounting
* `card.transaction.deleted` — auth reversed
* `card.transaction.invoiced` — has invoice number
* `receipt.fetched` — digital receipt URL
* `transaction.true.vat` — correct VAT from merchant
* `transaction.line.items` — purchase line items
* `card_holder.*` — lifecycle events
* `tpa.signed` — legal agreement done

## Next step

→ **[Quickstart](/getting-started/quickstart)** — full walkthrough from register to first webhook.