> ## 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.

# Issuer API Overview

> Reference for the OpenCard Issuer API — register cards and push transaction states under /api/v1/issuers/{slug}/ on api.opencard.io.

Card issuers use this API to **register cards** and **deliver transaction states** to OpenCard. Connected EMS apps receive the data via webhooks.

<Warning>
  This is **not** `receipts.opencard.io`. For digital receipt matching only → [Digital Receipts API](/api-reference/receipts/overview).
</Warning>

## Base URLs

| Environment | URL                               |
| ----------- | --------------------------------- |
| Sandbox     | `https://sandbox-api.opencard.io` |
| Production  | `https://api.opencard.io`         |

## Path prefix

```
/api/v1/issuers/{slug}/
```

`{slug}` is assigned at integration start (e.g. your program identifier in the URL).

## Auth

OAuth 2.0 client credentials → `POST /oauth/token`

→ [Authentication](/card-issuers/issuer-integration/authentication)

## Card endpoints

| Method   | Path                                                       | Description               |
| -------- | ---------------------------------------------------------- | ------------------------- |
| `POST`   | `/api/v1/issuers/{slug}/cards`                             | Create card               |
| `DELETE` | `/api/v1/issuers/{slug}/cards/{cardId}`                    | Delete card               |
| `PUT`    | `/api/v1/issuers/{slug}/cards/{cardId}`                    | Update card (boilerplate) |
| `GET`    | `/api/v1/issuers/{slug}/cards/{cardId}`                    | Get card (boilerplate)    |
| `GET`    | `/api/v1/issuers/{slug}/cards`                             | List cards (boilerplate)  |
| `POST`   | `/api/v1/issuers/{slug}/cards/{cardId}/transaction_states` | Create transaction state  |

Not every `{slug}` enables all card methods — see [Cards guide](/card-issuers/issuer-integration/cards#endpoints).

## Integration guides

| Guide                                                                     | Topic                             |
| ------------------------------------------------------------------------- | --------------------------------- |
| [How it works](/card-issuers/issuer-integration)                          | Flow and prerequisites            |
| [Onboarding](/card-issuers/issuer-integration/onboarding)                 | TPA and go-live                   |
| [Cards](/card-issuers/issuer-integration/cards)                           | Card registry                     |
| [Transaction states](/card-issuers/issuer-integration/transaction-states) | Lifecycle events                  |
| [TPA delivery](/card-issuers/issuer-integration/tpa-integration)          | Signed / terminated TPA callbacks |

Contact **[support@opencard.io](mailto:support@opencard.io)** for `client_id`, `client_secret`, scopes, and `{slug}`.